Category Archives: Quantum Physics
Quantum Computers Are Like Kaleidoscopes, Helping Illustrate Science and Technology – DISCOVER Magazine
Quantum computing is like Forrest Gumps box of chocolates: You never know what youre gonna get. Quantum phenomena the behavior of matter and energy at the atomic and subatomic levels are not definite, one thing or another. They are opaque clouds of possibility or, more precisely, probabilities. When someone observes a quantum system, it loses its quantum-ness and collapses into a definite state.
Quantum phenomena are mysterious and often counterintuitive. This makes quantum computing difficult to understand. People naturally reach for the familiar to attempt to explain the unfamiliar, and for quantum computing this usually means using traditional binary computing as a metaphor. But explaining quantum computing this way leads to major conceptual confusion, because at a base level the two are entirely different animals.
This problem highlights the often mistaken belief that common metaphors are more useful than exotic ones when explaining new technologies. Sometimes the opposite approach is more useful. The freshness of the metaphor should match the novelty of the discovery.
The uniqueness of quantum computers calls for an unusual metaphor. As a communications researcher who studies technology, I believe that quantum computers can be better understood as kaleidoscopes.
The gap between understanding classical and quantum computers is a wide chasm. Classical computers store and process information via transistors, which are electronic devices that take binary, deterministic states: one or zero, yes or no. Quantum computers, in contrast, handle information probabilistically at the atomic and subatomic levels.
Classical computers use the flow of electricity to sequentially open and close gates to record or manipulate information. Information flows through circuits, triggering actions through a series of switches that record information as ones and zeros. Using binary math, bits are the foundation of all things digital, from the apps on your phone to the account records at your bank and the Wi-Fi signals bouncing around your home.
In contrast, quantum computers use changes in the quantum states of atoms, ions, electrons or photons. Quantum computers link, or entangle, multiple quantum particles so that changes to one affect all the others. They then introduce interference patterns, like multiple stones tossed into a pond at the same time. Some waves combine to create higher peaks, while some waves and troughs combine to cancel each other out. Carefully calibrated interference patterns guide the quantum computer toward the solution of a problem.
Physicist Katie Mack explains quantum probability.
The term bit is a metaphor. The word suggests that during calculations, a computer can break up large values into tiny ones bits of information which electronic devices such as transistors can more easily process.
Using metaphors like this has a cost, though. They are not perfect. Metaphors are incomplete comparisons that transfer knowledge from something people know well to something they are working to understand. The bit metaphor ignores that the binary method does not deal with many types of different bits at once, as common sense might suggest. Instead, all bits are the same.
The smallest unit of a quantum computer is called the quantum bit, or qubit. But transferring the bit metaphor to quantum computing is even less adequate than using it for classical computing. Transferring a metaphor from one use to another blunts its effect.
The prevalent explanation of quantum computing is that while classical computers can store or process only a zero or one in a transistor or other computational unit, quantum computers supposedly store and handle both zero and one and other values in between at the same time through the process of superposition.
Superposition, however, does not store one or zero or any other number simultaneously. There is only an expectation that the values might be zero or one at the end of the computation. This quantum probability is the polar opposite of the binary method of storing information.
Driven by quantum sciences uncertainty principle, the probability that a qubit stores a one or zero is like Schroedingers cat, which can be either dead or alive, depending on when you observe it. But the two different values do not exist simultaneously during superposition. They exist only as probabilities, and an observer cannot determine when or how frequently those values existed before the observation ended the superposition.
Leaving behind these challenges to using traditional binary computing metaphors means embracing new metaphors to explain quantum computing.
The kaleidoscope metaphor is particularly apt to explain quantum processes. Kaleidoscopes can create infinitely diverse yet orderly patterns using a limited number of colored glass beads, mirror-dividing walls and light. Rotating the kaleidoscope enhances the effect, generating an infinitely variable spectacle of fleeting colors and shapes.
The shapes not only change but cant be reversed. If you turn the kaleidoscope in the opposite direction, the imagery will generally remain the same, but the exact composition of each shape or even their structures will vary as the beads randomly mingle with each other. In other words, while the beads, light and mirrors could replicate some patterns shown before, these are never absolutely the same.
If you dont have a kaleidoscope handy, this video is a good substitute.
Using the kaleidoscope metaphor, the solution a quantum computer provides the final pattern depends on when you stop the computing process. Quantum computing isnt about guessing the state of any given particle but using mathematical models of how the interaction among many particles in various states creates patterns, called quantum correlations.
Each final pattern is the answer to a problem posed to the quantum computer, and what you get in a quantum computing operation is a probability that a certain configuration will result.
Metaphors make the unknown manageable, approachable and discoverable. Approximating the meaning of a surprising object or phenomenon by extending an existing metaphor is a method that is as old as calling the edge of an ax its bit and its flat end its butt. The two metaphors take something we understand from everyday life very well, applying it to a technology that needs a specialized explanation of what it does. Calling the cutting edge of an ax a bit suggestively indicates what it does, adding the nuance that it changes the object it is applied to. When an ax shapes or splits a piece of wood, it takes a bite from it.
Metaphors, however, do much more than provide convenient labels and explanations of new processes. The words people use to describe new concepts change over time, expanding and taking on a life of their own.
When encountering dramatically different ideas, technologies or scientific phenomena, its important to use fresh and striking terms as windows to open the mind and increase understanding. Scientists and engineers seeking to explain new concepts would do well to seek out originality and master metaphors in other words, to think about words the way poets do.
Sorin Adam Matei is an Associate Dean for Research at Purdue University. This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Scientists Create The Thinnest Lens on Earth Using Quantum Physics – ScienceAlert
A quantum phenomenon has allowed scientists to develop a lens just three atoms thick, qualifying as the thinnest ever made.
Oddly, the innovative approach allows most wavelengths of light to pass right through a feature that could see it have huge potential in optical fiber communication and gadgets like augmented reality glasses.
The researchers who invented the lens, from the University of Amsterdam in the Netherlands and Stanford University in the US, say that their innovation will progress research into lenses of this type, as well as miniature electronic systems.
"The lens can be used in applications where the view through the lens should not be disturbed, but a small part of the light can be tapped to collect information," says Jorik van de Groep, a nanoscientist at the University of Amsterdam.
Rather than using a transparent material's curved surface to bend light in a process of refraction, incoming waves are instead focused by a series of grooved edges using diffraction.
The technology, known as a Fresnel lens or zone plate lens, has been used for centuries in the manufacture of thin, light-weight lenses, like those used in lighthouses.
To give the technique a quantum boost, the research team etched concentric rings into a thin layer of a semiconductor called tungsten disulfide (WS2). When WS2 absorbs light, its electrons move in a precise manner that leaves a gap that can be considered as a kind of particle in its own right.
Together, the electron and its 'hole' is form what's known as an exciton, which has properties that assist in the focussing efficiency of very specific wavelengths of light while letting other wavelengths pass through unaltered.
The size of the rings, and the distance between them, allowed the lens to focus red light a distance of 1 millimeter away. The team found while the lens works at room temperature, at lower temperatures its focusing capabilities became even more efficient.
Next, the researchers want to run more experiments to see how exciton behavior might be manipulated further, to improve the efficiency and capability of the lens. Future studies might involve optical coatings that can be placed on other materials, for instance, as well as variations in electrical charge.
"Excitons are very sensitive to the charge density in the material, and therefore we can change the refractive index of the material by applying a voltage," says van de Groep.
The research has been published in Nano Letters.
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Scientists Create The Thinnest Lens on Earth Using Quantum Physics - ScienceAlert
Shattering the Limits of Classical Physics: Quantum Entanglement Measures Earth’s Rotation Like Never Before – SciTechDaily
The experiment was pictured drawing a fiber Sagnac interferometric scheme inside a magnifying inset starting from a local position (Vienna, Austria) of the rotating Earth. Two indistinguishable photons are incident on a beam splitter cube, entanglement between them is created, and then they are coupled in the fiber interferometer. Credit: Marco Di Vita
A quantum physics experiment at the University of Vienna achieved groundbreaking precision in measuring Earths rotation using entangled photons.
The study utilizes an enhanced optical Sagnac interferometer that leverages quantum entanglement to detect rotational effects with unprecedented precision, offering potential breakthroughs in both quantum mechanics and general relativity.
A team of researchers carried out a pioneering experiment where they measured the effect of the rotation of Earth on quantum entangled photons. The work, led by Philip Walther at the University of Vienna, was published on June 14 in the journal Science Advances. It represents a significant achievement that pushes the boundaries of rotation sensitivity in entanglement-based sensors, potentially setting the stage for further exploration at the intersection between quantum mechanics and general relativity.
Optical Sagnac interferometers are the most sensitive devices to rotations. They have been pivotal in our understanding of fundamental physics since the early years of the last century, contributing to establishing Einsteins special theory of relativity. Today, their unparalleled precision makes them the ultimate tool for measuring rotational speeds, limited only by the boundaries of classical physics.
Sagnac interferometer built with 2-kilometers of optical fibers wrapped around 1.4 meter sided square aluminum frame. Credit: Raffaele Silvestri
Interferometers employing quantum entanglement have the potential to break those bounds. If two or more particles are entangled, only the overall state is known, while the state of the individual particle remains undetermined until measurement. This can be used to obtain more information per measurement than would be possible without it. However, the promised quantum leap in sensitivity has been hindered by the extremely delicate nature of entanglement.
Here is where the Vienna experiment made the difference. They built a giant optical fiber Sagnac interferometer and kept the noise low and stable for several hours. This enabled the detection of enough high-quality entangled photon pairs to outperform the rotation precision of previous quantum optical Sagnac interferometers by a thousand times.
In a Sagnac interferometer, two particles traveling in opposite directions of a rotating closed path reach the starting point at different times. With two entangled particles, it becomes spooky: they behave like a single particle testing both directions simultaneously while accumulating twice the time delay compared to the scenario where no entanglement is present. This unique property is known as super-resolution. In the actual experiment, two entangled photons were propagating inside a 2-kilometer-long optical fiber wound onto a huge coil, realizing an interferometer with an effective area of more than 700 square meters.
A significant hurdle the researchers faced was isolating and extracting Earths steady rotation signal. The core of the matter, explains lead author Raffaele Silvestri, lays in establishing a reference point for our measurement, where light remains unaffected by Earths rotational effect. Given our inability to halt Earths spinning, we devised a workaround: splitting the optical fiber into two equal-length coils and connecting them via an optical switch.
By toggling the switch on and off the researchers could effectively cancel the rotation signal at will, which also allowed them to extend the stability of their large apparatus. We have basically tricked the light into thinking its in a non-rotating universe, says Silvestri.
The experiment, which was conducted as part of the research network TURIS hosted by the University of Vienna and the Austrian Academy of Sciences, has successfully observed the effect of the rotation of Earth on a maximally entangled two-photon state. This confirms the interaction between rotating reference systems and quantum entanglement, as described in Einsteins special theory of relativity and quantum mechanics, with a thousand-fold precision improvement compared to previous experiments.
That represents a significant milestone since, a century after the first observation of Earths rotation with light, the entanglement of individual quanta of light has finally entered the same sensitivity regimes, says Haocun Yu, who worked on this experiment as a Marie-Curie Postdoctoral Fellow.
I believe our result and methodology will set the ground to further improvements in the rotation sensitivity of entanglement-based sensors. This could open the way for future experiments testing the behavior of quantum entanglement through the curves of spacetime, adds Philip Walther.
Reference: Experimental observation of Earths rotation with quantum entanglement by Raffaele Silvestri, Haocun Yu, Teodor Strmberg, Christopher Hilweg, Robert W. Peterson and Philip Walther, 14 June 2024, Science Advances. DOI: 10.1126/sciadv.ado0215
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From Theory to Reality: Scientists Unveil Quadruple-Q Hedgehog Lattices – SciTechDaily
Recent discoveries in materials such as manganese germanide have unveiled structures that behave like magnetic monopoles. Researchers have identified new dynamic properties in these structures, potentially paving the way for innovative technologies in spintronics and fundamental physics research. Credit: SciTechDaily.com
Magnetic monopoles are elementary particles with isolated magnetic charges in three dimensions. In other words, they behave as isolated north or south poles of a magnet. Magnetic monopoles have attracted continuous research interest since physicist Paul Diracs first proposal in 1931.
However, real magnetic monopoles have not yet been observed and their existence remains an open question. On the other hand, scientists have discovered quasi-particles that mathematically behave as magnetic monopoles in condensed matter systems, resulting in interesting phenomena.
Recently, researchers discovered that a material called manganese germanide (MnGe) has a unique periodic structure, formed by special magnetic configurations called hedgehogs and antihedgehogs, which is called a magnetic hedgehog lattice. In these special configurations, the magnetic moments point radially outward (hedgehog) or inward (antihedgehog), resembling the spines of a hedgehog. These hedgehogs and antihedgehogs act like magnetic monopoles and antimonopoles, serving as sources or sinks of emergent magnetic fields.
The collective excitation modes of hedgehog lattices are governed by oscillation of Dirac strings, connecting a hedgehog and an antihedgehog, which can be used to study their spatial configuration in magnets. Credit: Masahito Mochizuki from Waseda University
MnGe exhibits what is known as a triple-Q hedgehog lattice. However, recent experiments have shown that the substitution of Ge with Si (MnSi1-xGex) transforms the arrangement into the quadruple-Q hedgehog lattice (4Q-HL). This new arrangement, also found in the perovskite ferrite SrFeO3, provides a promising avenue for studying and controlling the properties of hedgehog lattices. Moreover, these magnetic monopoles can also induce electric fields through moving following Maxwells laws of electromagnetism. To understand the resulting new physical phenomena, it is essential to study the inherent excitations of hedgehog lattices.
In a recent study, Professor Masahito Mochizuki and Ph.D. course student Rintaro Eto, both from the Department of Applied Physics at Waseda University, theoretically studied the collective excitation modes of 4Q-HLs in MnSi1-xGex and SrFeO3. Our research clarified the unknown dynamical nature of emergent magnetic monopoles in magnetic materials for the first time. This can inspire future experiments on hedgehog-hosting materials with applications in electronic devices and for bridging particle physics and condensed-matter physics, says Mochizuki. Their study was published in the journal Physical Review Letters on 31 May 2024.
Utilizing the three-dimensional Kondo-lattice model, the researchers reproduced the two distinct 4Q-HLs found in MnSi1-xGex and SrFeO3 and analyzed their dynamical properties. They discovered that the 4Q-HLs have collective excitation modes associated with the oscillation of Dirac strings. A Dirac string is a theoretical concept in quantum mechanics that describes a string that connects a magnetic monopole and a magnetic antimonopole, in this case, a hedgehog and an antihedgehog.
The researchers found that the number of these excitation modes depends on the number and configuration of Dirac strings, offering a way to experimentally determine the spatial configuration of hedgehogs and antihedgehogs and their unique topology in real magnets such as MnSi1-xGex and SrFeO3. This finding offers insights into the dynamics of hedgehog lattices in other magnets as well. Moreover, the finding enables us to switch on and off the excitation modes through controlling the presence or absence of the Dirac strings with external magnetic field.
Explaining the significance of their results, Eto remarks, The collective spin excitation modes revealed in the study are elementary excitations that directly reflect the presence (or absence) of emergent magnetic monopoles. Thus, our findings will be a fundamental guideline for studying the more detailed dynamical nature of emergent monopoles in magnetic materials in the future. Moreover, they might become the building blocks of novel field-switchable spintronic devices such as nano-sized power generators, light-voltage converters, and light/microwave filters based on emergent electromagnetism.
These discoveries have the potential to open new research avenues in fundamental physics and lead to the development of new technologies involving emergent magnetic monopoles in magnets.
Reference: Theory of Collective Excitations in the Quadruple- Magnetic Hedgehog Lattices by Rintaro Eto and Masahito Mochizuki, 31 May 2024, Physical Review Letters. DOI: 10.1103/PhysRevLett.132.226705
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From Theory to Reality: Scientists Unveil Quadruple-Q Hedgehog Lattices - SciTechDaily
Time May Actually Be One Big Illusion, New Study Says – Popular Mechanics
Time has puzzled scientists for many decades. Does it meaningfully exist apart from our experience of it as everything moves toward the disintegration of
In new research published in the American Physical Society's peer-reviewed journal Physical Review A, scientists from Italy (led by Alessandro Coppo) try to translate one theory of time into real lifeor, at least, closer to it. The theory is called Page and Wootters mechanism, and Coppo has studied it for years. Its a quantum mechanics idea that dates back to 1983.
While general relativity (in the classical physics model) lets time be a variablelike the perception-dependent difference between time on Earth and time in space in stories like Interstellarquantum physics requires it to be nailed down. That means instead of a dependent variable (something defined by an external property, like local gravity or an objects distance from Earth), time must be independent, and there must be some way to measure it as such.
This may seem counterintuitive. After all, quantum mechanics is considered the newer version of thingsthe one that destabilizes the foundation of physics in order to be reconciled with the classical model. But time has a unique role in quantum systems. After all, everything in a particular time, defined in some objective way, is knitted together through quantum interactions until it forms a capture of the entire universe (if you zoom out enough).
In their paper, Coppo and his coauthors turn the Page and Wootters approach into a real concept for a clock. Within quantum physics, a clock isnt much like the one you wear on your wrist or hang in your officeits anything that has a predictable and uniform behavior that can be used as a measurement. (For example, this 2021 Quanta article lists increasingly stinky garbage as a kind of clock!)
New Scientist explains that Page and Wootters wondered if our world is so quantumly entangled within itself that any visible passing of time is a symptom of entanglement. They also suggested that we ourselves are implicated in that entanglement just by seeing the passage of timebecause someone outside of the entangled system would see it standing still. The clock, therefore, is the item within the entangled system that shows time passing.
Its easy to see why this theory has stayed mostly abstract for over 40 years. To turn it into something with measurements based in real life observation, scientists took iconic physics equations and restricted them to conditions that match the Page and Wootters scenario. They considered two systems that are entangled but do not interact, where one system is a harmonic oscillatorlike a quartz timing in a watch, or a pendulum.
Their solution may prove to be consistent within classical and quantum mechanics, because when enough particles are placed into each quantum systemwhen it reaches the threshold called macroscopic, based on massthe systems align with classical physics as well.
Thats a big dealif our entire, very macroscopic world fits into this definition of time based on entanglement, it means everything around us is entangled. Things would need to be entangled almost by definition in order to be part of our observable world. And it would mean that anything we see where time passes (no matter how far away it is) is linked with us in a vital way.
Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all.
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Time May Actually Be One Big Illusion, New Study Says - Popular Mechanics
Quantum entangled photons used to measure the Earth’s rotation – Earth.com
In a remarkable feat of scientific exploration, a team of researchers has successfully measured the effect of Earths rotation on quantum entangled photons.
This pioneering experiment, conducted by a group led by Philip Walther at the University of Vienna, pushes the boundaries of rotation sensitivity in entanglement-based sensors.
These brilliant scientists have brought the world a step closer to the fascinating intersection between quantum mechanics and general relativity.
Their research represents a significant milestone in our understanding of the intricate relationship between rotating reference systems and quantum entanglement.
By employing a giant optical fiber Sagnac interferometer and maintaining low and stable noise levels for several hours, the team achieved a thousand-fold improvement in rotation precision compared to previous quantum optical Sagnac interferometers.
Optical Sagnac interferometers have long been recognized as the most sensitive devices for measuring rotations.
These instruments have played a crucial role in shaping our understanding of fundamental physics since the early years of the last century, contributing to the establishment of Einsteins special theory of relativity.
Today, their unparalleled precision makes them the ultimate tool for measuring rotational speeds, limited only by the boundaries of classical physics.
However, interferometers employing quantum entanglement to measure Earths rotation have the potential to break those bounds.
When two or more particles are entangled, only the overall state is known, while the state of the individual particle remains undetermined until measurement.
This unique property can be harnessed to obtain more information per measurement than would be possible without entanglement.
Despite the immense potential of entanglement-based sensors, their practical implementation has been hindered by the extremely delicate nature of entanglement.
This is where the Vienna experiment made a significant breakthrough.
The researchers constructed a massive optical fiber Sagnac interferometer, with two entangled photons propagating inside a 2-kilometer-long optical fiber wound onto a huge coil.
This setup realized an interferometer with an effective area of more than 700 square meters.
By keeping the noise low and stable for several hours, the team was able to detect enough high-quality entangled photon pairs to outperform the rotation precision of previous quantum optical Sagnac interferometers by a thousand times.
One of the major challenges faced by the researchers was isolating and extracting Earths steady rotation signal.
The core of the matter lays in establishing a reference point for our measurement, where light remains unaffected by Earths rotational effect, lead author Raffaele Silvestri explains.
Given our inability to halt Earths from spinning, we devised a workaround: splitting the optical fiber into two equal-length coils and connecting them via an optical switch.
By toggling the switch on and off, the researchers could effectively cancel the rotation signal at will, allowing them to extend the stability of their large apparatus.
We have basically tricked the light into thinking its in a non-rotating universe, Silvestri concluded.
In a Sagnac interferometer, two particles traveling in opposite directions of a rotating closed path reach the starting point at different times.
However, when two entangled particles are involved, something extraordinary happens: they behave like a single particle testing both directions simultaneously while accumulating twice the time delay compared to the scenario where no entanglement is present.
This unique property is known as super-resolution.
The experiment, conducted as part of the research network TURIS hosted by the University of Vienna and the Austrian Academy of Sciences, successfully observed the effect of Earths rotation on a maximally entangled two-photon state.
This confirmation of the interaction between rotating reference systems and quantum entanglement, as described in Einsteins special theory of relativity and quantum mechanics, represents a thousand-fold precision improvement compared to previous experiments.
That represents a significant milestone since, a century after the first observation of Earths rotation with light, the entanglement of individual quanta of light has finally entered the same sensitivity regimes, says Haocun Yu, who worked on this experiment as a Marie-Curie Postdoctoral Fellow.
The successful demonstration of this methodology opens up exciting possibilities for future research.
Philip Walther, the lead researcher, believes that their result and methodology will set the ground for further improvements in the rotation sensitivity of entanglement-based sensors.
This could open the way for future experiments testing the behavior of quantum entanglement through the curves of spacetime, he adds.
This fascinating experiment marks a significant milestone in our understanding of the intricate relationship between quantum entanglement and the effects of Earths rotation.
By successfully measuring the influence of our planets spin on entangled photons with unprecedented precision, this research confirms the predictions of Einsteins special theory of relativity and quantum mechanics while opening the door to a new era of exploration at the fascinating intersection of these two fundamental fields.
As scientists continue to push the boundaries of entanglement-based sensors, we stand on the brink of unraveling the mysteries of spacetime and gaining a deeper understanding of the universes most fundamental workings.
The full study was published in the journal Science Advances.
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Quantum entangled photons used to measure the Earth's rotation - Earth.com
A Missing Piece in the Big Bang Theory Has Surfaced – AOL
A Missing Piece in the Big Bang Theory Has ArrivedAbhishek Mehta - Getty Images
Combining different pieces from Big Bang cosmology could help explain an issue we have today.
The Hubble constant, the speed of expansion of our universe, is not observed with consistency.
These scientists suggest that not-well-understood quantum gravity could account for the gap.
In research published earlier this year, physicists from the University of Hyderabad in India say theyre on the path to solving one of the universes biggest outstanding problems. Since Edwin Hubble realized the universe is always expanding nearly 100 years ago, scientists have used the Hubble constant in calculations on virtually every scale in the universe. But today, estimates for the Hubble constant dont always align, with a difference of up to 10 percent between calculations made using different methods. (When someone at NASA mixes up meters and yards and loses an entire spacecraft, thats not even a full 10 percent deviation.)
The paper appears in the peer reviewed journal Classical and Quantum Gravity. The journal has an ongoing, periodically updated focus issue specifically about this measurement tension, and the editors explain the problem therescientists cant say for sure that the different Hubble constants measured are actually different, rather than just observation or calibration issues.
But the authors of the new paper, physicist P.K. Suresh and his research fellow (referred to as just Anupama B.) say that most measurements taken now are reliable. Instrumentation only continues to improveweve all seen those generation-defining, poster-quality photos of the far-out planets, for example. If the measurements on the local and faraway levels are indeed sound, then something is missing.
Its here where they introduce quantum gravity as a possible factor. This variablewhich, to be honest, is another enigmatic placeholder in some wayscould close the gap in Hubble constant observations. Thats because, as the authors propose, quantum gravity could have affected the rate of change at which the universe expanded itself. When a constant can have a variable rate of change, its easy to see why researchers tend to drop the constant label and instead call the fatcor simply H0, H1, and so on to designate which version of the measurement is in play.
The researchers explain that during inflationthe rapid growth of the universe immediately following the Big Bangthere may not have been a single, uniform inflation zone. Instead, more and more scientists are theorizing around the idea of multi field inflation. The idea originated to explain another measurement discrepancy: the number of particles in particular places or times, compared with the massive speed of inflation overall.
If a theory could help explain one gap in our codified equations for how inflation works, it makes sense to try that theory to find other missing pieces. These researchers used what is called the hybrid inflationary model, which describes two fields: one inflating and one rolling over like a waterfall. By accounting for quantum gravity, they found they were able to reconcile H0the current Hubble constantwith both H1 (during inflation) and HT (during phase transition). Just one adjusted equation with a parameter for quantum gravity could draw a curve that includes all three data points.
The researchers say that to resolve the Hubble tension, one must also establish and validate the inflation model linked with it. Cosmology faces unique challenges, including the ongoing question of quantum gravity itself. So, trying to stake out a specific model like this involves choosing and stabilizing other variables that may not be well understood or have a consensus... yet.
But, Suresh told Live Science, that cant stop researchers from pushing forward. Our equation doesnt need to account for everything, Suresh said, but that does not prevent us from testing quantum gravity or its effects experimentally.
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Quantum entanglement precisely measures Earth’s spin for first time – Study Finds
VIENNA In 1913, French physicist Georges Sagnac demonstrated that light travels at different speeds in opposite directions in a spinning frame of reference an effect that came to be known as the Sagnac effect. Over a century later, a team of physicists at the University of Vienna has given this classic experiment a quantum twist. By injecting entangled photons into a rotating fiber optic setup, theyve measured the rotation of the Earth itself with unprecedented precision, opening up exciting new possibilities for probing the intersection of quantum mechanics and gravity.
The team, led by Raffaele Silvestri and Philip Walther and publishing their work in Science Advances, constructed a massive quantum-enhanced Sagnac interferometer a device that splits light into two beams that travel in opposite directions around a closed path before recombining. Due to the Earths rotation, the light traveling in the direction of the spin experiences a slightly shorter path than the light traveling against it, creating a detectable interference pattern when the beams remix.
But the Vienna team wasnt content with ordinary light. They used pairs of photons that were quantum mechanically entangled, meaning their properties were inextricably linked regardless of the distance between them. When these entangled photons were sent in opposite directions around the 715 square meter fiber optic loop, the researchers observed a telltale doubling of the phase shift compared to unentangled photons a signature of the photons spooky quantum connection.
Remarkably, this setup allowed the team to measure the Earths rotation with a sensitivity of five microradians per second the most precise quantum optical measurement of this kind to date. Thats like being able to detect a one-degree turn of a basketball in New York City from the distance of Los Angeles.
To achieve this, the researchers began by generating pairs of photons that were entangled in their polarization states using a process called spontaneous parametric down-conversion. These photon pairs were then sent into a Sagnac interferometer constructed from a two-kilometer long spool of optical fiber, with the two photons from each pair traveling in opposite directions.
A key innovation was the inclusion of an optical switch that could instantly change the effective area of the interferometer to zero. By toggling this switch on and off, the researchers could compare the interference patterns with and without the Earths rotation signal, allowing them to isolate the effect from other noise sources.
To further increase the sensitivity, the team varied the orientation of the fiber loop relative to the Earths rotational axis, mapping out the sinusoidal dependence of the Sagnac phase shift. This allowed them to precisely calibrate their setup and extract the maximum possible signal.
The core of the matter lies in establishing a reference point for our measurement, where light remains unaffected by Earths rotational effect. Given our inability to halt Earth from spinning, we devised a workaround: splitting the optical fiber into two equal-length coils and connecting them via an optical switch, explains lead author Raffaele Silvestri in a media release.
The results were striking. When entangled photon pairs were used, the observed phase shift was consistently twice as large as for individual unentangled photons, regardless of the interferometers orientation. This is a direct consequence of the quantum mechanical nature of the entangled state.
By fitting their data to the theoretical model of the Sagnac effect, the researchers determined the Earths rotation rate to be approximately 7.3 x 10^-5 radians per second, in excellent agreement with the accepted value. The precision achieved is orders of magnitude better than previous quantum optical measurements and begins to approach the regime where effects from general relativity come into play.
We have basically tricked the light into thinking its in a non-rotating universe, says Silvestri.
While groundbreaking, the experiment still faces some limitations. The main factor restricting the sensitivity is noise from environmental vibrations and temperature fluctuations, which can slightly change the effective size of the fiber loop. As the researchers scale up to even larger interferometers, these effects will need to be carefully controlled.
Additionally, the current setup can only measure the magnitude of the Earths rotation, not its direction. Future experiments could potentially use more sophisticated quantum states to gain directional information as well.
Despite these limitations, this work has profound implications. As the precision of quantum sensors continues to improve, it may soon be possible to observe subtle effects that arise from the interplay of quantum mechanics and gravity a major unsolved problem in theoretical physics.
For instance, some theories predict that the gravitational field of a spinning mass can cause minute changes in the entanglement between particles. The techniques demonstrated in this experiment could potentially be adapted to search for such effects, providing a much-needed experimental probe of quantum gravity.
Moreover, ultra-precise quantum gyroscopes like this one could have a wide range of practical applications, from navigation of autonomous vehicles to tests of fundamental physics. By pushing the limits of quantum metrology, this research opens the door to a new era of ultra-precise sensing and tests of natures most elusive phenomena.
In the end, this experiment is a testament to the power of quantum entanglement and the ingenuity of experimental physicists. By applying cutting-edge quantum techniques to a century-old classic, Silvestri, Walther, and their colleagues have not only measured the spin of our planet with record-breaking accuracy but also brought us one step closer to unraveling the deep mysteries that lie at the heart of space, time, and quantum reality. As we stand on the cusp of a quantum revolution in sensing and metrology, the future looks bright and more than a little entangled.
StudyFinds Editor-in-ChiefSteve Fink contributedto this report.
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Quantum entanglement precisely measures Earth's spin for first time - Study Finds
Earth’s rotation measured 1000x better with quantum entanglement – Interesting Engineering
Researchers at the University of Vienna led by Philip Walther just pioneered the field of quantum mechanics and general relativity by measuring the effect of the rotation of Earth on quantum entangled photons, as stated in a press release.
In the Vienna experiment, they used an interferometer, which is the most sensitive to rotations. Its unparalleled precision makes it the ultimate tool for measuring rotational speeds, limited only by the boundaries of classical physics.
Interferometers employing quantum entanglement have the potential to break those bounds. If two or more particles are entangled, only the overall state is known, while the state of the individual particle remains undetermined until measurement.
This can be used to obtain more information per measurement than would be possible without it. However, the promised quantum leap in sensitivity has been hindered by the extremely delicate nature of entanglement which is prone to decoherence, lead author Raffaele Silvestri explained to Interesting Engineering. Until now.
Here is where the Vienna experiment made the difference. They built a giant optical fibre Sagnac interferometer and kept the noise low and stable for several hours. This enabled the detection of enough high-quality entangled photon pairs such to outperform the rotation precision of previous quantum optical Sagnac interferometers by a thousand.
It is extremely challenging to make precision measurements in large-scale devices by employing these probe states, Silvestri extrapolated to Interesting Engineering.
We have overcome those hurdles by increasing, with innovative techniques, the long-term stability in time of our huge interferometer.'
A significant hurdle the researchers faced was isolating and extracting Earths steady rotation signal.
The core of the matter lays in establishing a reference point for our measurement, where light remains unaffected by Earths rotational effect, Silvestri said in a press release.
Given our inability to halt Earths from spinning, we devised a workaround: splitting the optical fibre into two equal-length coils and connecting them via an optical switch.
By toggling the switch on and off, the researchers could effectively cancel the rotation signal at will, which also allowed them to extend the stability of their large apparatus.
We have basically tricked the light into thinking its in a non-rotating universe, added Silvestri.
To clarify, Silvestri told Interesting Engineering humorously to not take it too literally.
They swapped the propagation direction of the two counter-propagating photons for half of the propagation length in the optical fiber. This means that when the photons come back to the starting point the delay that they have accumulated, which quantifies Earth rotational speed, is null.
So being that the interferometer is attached to the Earths surface and its rotating with it, the Earths rotation-induced effect is cancelled. Its almost as if the photons dont feel or see any rotation in the end, tricked into thinking they are in a non-rotating reference frame AKA universe.
This enables them to compare the behavior of the entangled state from a rotating to an effectively non-rotating reference frame and brings also several technical advantages as noise suppression and higher stability in the long term.
This technique has never been employed in a quantum Sagnac interferometer and is an innovative invention for this reason, he concluded.
The experiment, which was conducted as part of the research network TURIS hosted by the University of Vienna and the Austrian Academy of Sciences, has successfully observed the effect of the rotation of Earth on a maximally entangled two-photon state.
This confirms the interaction between rotating reference systems and quantum entanglement, as described in Einsteins special theory of relativity and quantum mechanics, with a thousand-fold precision improvement compared to previous experiments.
That represents a significant milestone since, a century after the first observation of Earths rotation with light, the entanglement of individual quanta of light has finally entered the same sensitivity regimes, said Haocun Yu, who worked on this experiment as a Marie-Curie Postdoctoral Fellow.
I believe our result and methodology will set the ground to further improvements in the rotation sensitivity of entanglement-based sensors. This could open the way for future experiments testing the behavior of quantum entanglement through the curves of spacetime, added Philip Walther.
In other words, the next step, Silvestri said, would be increasing the sensitivity by a significant amount to be able to detect general relativistic effects as Frame-Dragging (or Lense-Thirring) on an entangled photon pair. This is a gravitational effect that is predicted by Einsteins general theory of relativity in presence of a rotating massive body, as a rotating Earth drags its spacetime curvature and it simply manifests itself as a small correction to the Earth rotational speed.
This measurement would represent the first experimental test of the behavior of quantum mechanics in curved spacetimes, shining light into this unexplored regime.
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Maria Mocerino Originally from LA, Maria Mocerino has been published in Business Insider, The Irish Examiner, The Rogue Mag, Chacruna Institute for Psychedelic Plant Medicines, and now Interesting Engineering.
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Earth's rotation measured 1000x better with quantum entanglement - Interesting Engineering
The Pentagon Is Trying to Build a Laser That Never Fails – Yahoo News Canada
Lasers are a fundamental technology of todays society, but this amplified light still suffers from shortcomingsextreme temperatures, long distances, or even just fog.
Researchers from the Washington University in St. Louis and Texas A&M University are turning to quantum mechanics to create an entangled laser than can overcome these pitfalls.
The research is being conducted via a two-year, $1 million grant from the Defense Advanced Research Projects Agency (DARPA), which can probably think of a few use cases for a quantum laser.
Light Amplification by Stimulated Emission of Radiation, otherwise known as the laser, fundamentally changed human society upon its introduction in the early 1960s. The uses for lasers seem almost endless, and have rearranged how we communicate, perform surgeries, and even pay for groceries. In other words, we very much live in the laser era.
However, this ubiquitous technology isnt without its shortcomings. Because lasers are essentially just the optical amplifications of light, theyre still subject to failing in adverse conditionswhether that be fog, extreme temperatures, or even just long distances.
Now, scientists at Washington University in St. Louis and Texas A&M University are turning to quantum mechanics to solve these laser-based shortcomings. The research will be conducted thanks to a two-year, $1 million grant from the Defense Advanced Research Projects Agency (DARPA) and will be led by Washington University associate professor Jung-Tsung Shen, who hopes to develop a prototype device called a quantum photonic-dimer laser.
As its name suggests, this device is built around concepts from quantum mechanics. The idea is that two carefully controlled particles of light (a.k.a. photonic dimers) can be used to create a powerful laser beam. The quantum part of the equation comes in when these two particles are entangled, which can help protect from some of the deleterious effects lasers can face in challenging environmentswhen charge is applied to one photon, it directly applies to the other.
Photons encode information when they travel, but the travel through the atmosphere is very damaging to them, Shen said in a press statement. When two photons are bound together, they still suffer the effects of the atmosphere, but they can protect each other so that some phase information can still be preserved.
As you can probably imagine, entangling two photons isnt exactly easy, especially since they dont have a charge. Shen says he instead glued two different-colored photons together, which then exhibited the behavior of a blue photon. These entangled photons can then be tweaked to work optimally in fog, extreme temperatures, or any other adverse condition. This would be a huge boon for both communication and imaging, which can be specifically limited by atmosphere and distance.
Quantum entanglement is a correlation between photons, Shen said in a press statement. We are trying to exploit the property of entanglement to do something innovative. The entanglement can do many things that we can only dream of this is just the tip of the iceberg.
Researchers around the world are busy applying quantum mechanical properties to classical technologies. Last year, a French research team reported that their quantum radarwhich similarly uses quantum entanglement techniquesoutperformed classical radar by 20 percent. Researchers are also hard at work creating a quantum internet that will one day transmit information in quantum state, which could increase security and improve the study of materials.
So, while the laser was no doubt a world-changing invention, its revolutionary introduction may only be the first chapter of its technological journal.
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The Pentagon Is Trying to Build a Laser That Never Fails - Yahoo News Canada