Ordinarily, light particles photons dont interact. If two photons collide in a vacuum, they simply pass through each other.
An efficient way to make photons interact could open new prospects for both classical optics and quantum computing, an experimental technology that promises large speedups on some types of calculations.
In recent years, physicists have enabled photon-photon interactions using atoms of rare elements cooled to very low temperatures.
But in the latest issue of Physical Review Letters, MIT researchers describe a new technique for enabling photon-photon interactions at room temperature, using a silicon crystal with distinctive patterns etched into it. In physics jargon, the crystal introduces nonlinearities into the transmission of an optical signal.
All of these approaches that had atoms or atom-like particles require low temperatures and work over a narrow frequency band, says Dirk Englund, an associate professor of electrical engineering and computer science at MIT and senior author on the new paper. Its been a holy grail to come up with methods to realize single-photon-level nonlinearities at room temperature under ambient conditions.
Joining Englund on the paper are Hyeongrak Choi, a graduate student in electrical engineering and computer science, and Mikkel Heuck, who was a postdoc in Englunds lab when the work was done and is now at the Technical University of Denmark.
Quantum computers harness a strange physical property called superposition, in which a quantum particle can be said to inhabit two contradictory states at the same time. The spin, or magnetic orientation, of an electron, for instance, could be both up and down at the same time; the polarization of a photon could be both vertical and horizontal.
If a string of quantum bits or qubits, the quantum analog of the bits in a classical computer is in superposition, it can, in some sense, canvass multiple solutions to the same problem simultaneously, which is why quantum computers promise speedups.
Most experimental qubits use ions trapped in oscillating magnetic fields, superconducting circuits, or like Englunds own research defects in the crystal structure of diamonds. With all these technologies, however, superpositions are difficult to maintain.
Because photons arent very susceptible to interactions with the environment, theyre great at maintaining superposition; but for the same reason, theyre difficult to control. And quantum computing depends on the ability to send control signals to the qubits.
Thats where the MIT researchers new work comes in. If a single photon enters their device, it will pass through unimpeded. But if two photons in the right quantum states try to enter the device, theyll be reflected back.
The quantum state of one of the photons can thus be thought of as controlling the quantum state of the other. And quantum information theory has established that simple quantum gates of this type are all that is necessary to build a universal quantum computer.
The researchers device consists of a long, narrow, rectangular silicon crystal with regularly spaced holes etched into it. The holes are widest at the ends of the rectangle, and they narrow toward its center. Connecting the two middle holes is an even narrower channel, and at its center, on opposite sides, are two sharp concentric tips. The pattern of holes temporarily traps light in the device, and the concentric tips concentrate the electric field of the trapped light.
The researchers prototyped the device and showed that it both confined light and concentrated the lights electric field to the degree predicted by their theoretical models. But turning the device into a quantum gate would require another component, a dielectric sandwiched between the tips. (A dielectric is a material that is ordinarily electrically insulating but will become polarized all its positive and negative charges will align in the same direction when exposed to an electric field.)
When a light wave passes close to a dielectric, its electric field will slightly displace the electrons of the dielectrics atoms. When the electrons spring back, they wobble, like a childs swing when its pushed too hard. This is the nonlinearity that the researchers system exploits.
The size and spacing of the holes in the device are tailored to a specific light frequency the devices resonance frequency. But the nonlinear wobbling of the dielectrics electrons should shift that frequency.
Ordinarily, that shift is mild enough to be negligible. But because the sharp tips in the researchers device concentrate the electric fields of entering photons, they also exaggerate the shift. A single photon could still get through the device. But if two photons attempted to enter it, the shift would be so dramatic that theyd be repulsed.
The device can be configured so that the dramatic shift in resonance frequency occurs only if the photons attempting to enter it have particular quantum properties specific combinations of polarization or phase, for instance. The quantum state of one photon could thus determine the way in which the other photon is handled, the basic requirement for a quantum gate.
Englund emphasizes that the new research will not yield a working quantum computer in the immediate future. Too often, light entering the prototype is still either scattered or absorbed, and the quantum states of the photons can become slightly distorted. But other applications may be more feasible in the near term. For instance, a version of the device could provide a reliable source of single photons, which would greatly abet a range of research in quantum information science and communications.
This work is quite remarkable and unique because it shows strong light-matter interaction, localization of light, and relatively long-time storage of photons at such a tiny scale in a semiconductor, says Mohammad Soltani, a nanophotonics researcher in Raytheon BBN Technologies Quantum Information Processing Group. It can enable things that were questionable before, like nonlinear single-photon gates for quantum information. It works at room temperature, its solid-state, and its compatible with semiconductor manufacturing. This work is among the most promising to date for practical devices, such as quantum information devices.
- This is what a 50-qubit quantum computer looks like - January 15th, 2018
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- Quantum computer a possibility in 10 years - News.com.au - NEWS.com.au - September 7th, 2017
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- The Future of AI: From Quantum Computing to the Internet of Things - Outer Places - September 4th, 2017
- We're About to Cross The 'Quantum Supremacy' Limit in Computing - ScienceAlert - September 2nd, 2017
- Explaining the Most Recent Record for Quantum Computing: A 51-Qubit Quantum Computer Array - All About Circuits - September 2nd, 2017
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- Australia gets quantum computing company - ACS (registration) - August 28th, 2017
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- Introducing Australia's first quantum computing hardware company - CIO Australia - August 23rd, 2017
- What is quantum computer? - Definition from WhatIs.com - August 22nd, 2017
- Hype and cash are muddying public understanding of quantum computing - The Conversation AU - August 22nd, 2017
- Finns chill out quantum computers with qubit refrigerator to cut out errors - ZDNet - August 22nd, 2017
- UNSW joins with government and business to keep quantum computing technology in Australia - The Australian Financial Review - August 22nd, 2017
- 'Tools of DESTRUCTION' Quantum computers WILL wreak havoc ... - Express.co.uk - August 19th, 2017
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- No, Quantum Teleportation Won't Let Us Send Instant Messages to Alpha Centauri - Air & Space Magazine - August 12th, 2017
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- Closing In On Quantum Computing | WIRED - August 11th, 2017
- World's Leading Physicist Says Quantum Computers Are Tools of Destruction, Not Creation - Futurism - August 10th, 2017
- Will you be able to trust a quantum computer? - Digital Journal - August 9th, 2017
- New Methods of Controlling Electrons Could be Major in Quantum Computing - TrendinTech - August 5th, 2017
- Exactly what could quantum computers do? - Electronics Weekly - August 4th, 2017
- What is quantum computing and why does the future of Earth depend on it? - Alphr - August 2nd, 2017
- The Age of Quantum Computers is upon us! - Gizbot - August 2nd, 2017
- Ultracold molecules hold promise for quantum computing | MIT News - MIT News - August 1st, 2017
- Clarifiying complex chemical processes with quantum computers - Phys.Org - August 1st, 2017
- When Will Quantum Computers Be Consumer Products? - Futurism - August 1st, 2017
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- Quantum computers compete for supremacy - Salon - July 10th, 2017
- Quantum Computers Compete for "Supremacy" - Scientific American - July 5th, 2017
- Less is more for Canadian quantum computing researchers - ITworld - July 4th, 2017
- New method could enable more stable and scalable quantum ... - Phys.Org - July 4th, 2017
- Volkswagen buys D-Wave quantum computers which sell for $15 million each - Robotics and Automation News (press release) (registration) - July 2nd, 2017
- 6 Things Quantum Computers Will Be Incredibly Useful For - Singularity Hub - July 1st, 2017
- Quantum Machine Learning Computer Hybrids at the Center of New Start-Ups - TrendinTech - June 20th, 2017
- Israel Enters Quantum Computer Race, Placing Encryption at Ever-Greater Risk - Sputnik International - June 20th, 2017
- Prototype device enables photon-photon interactions at room ... - Phys.Org - June 20th, 2017
- The Quantum Computer Factory That's Taking on Google and IBM - WIRED - June 20th, 2017
- Get ahead in quantum computing AND attract Goldman Sachs - eFinancialCareers - June 16th, 2017
- KPN CISO details Quantum computing attack dangers - Mobile World Live - June 16th, 2017
- Quantum Computing Technologies markets will reach $10.7 billion by 2024 - PR Newswire (press release) - June 14th, 2017
- From the Abacus to Supercomputers to Quantum Computers - Duke Today - June 13th, 2017
- Quantum Computers Will Analyze Every Financial Model at Once - Singularity Hub - June 13th, 2017
- Are Enterprises Ready to Take a Quantum Leap? - IT Business Edge - June 13th, 2017
- Scientists May Have Found a Way to Combat Quantum Computer Blockchain Hacking - Futurism - June 13th, 2017
- Microsoft and Purdue work on scalable topological quantum computer - Next Big Future - June 13th, 2017
- Doped Diamonds Push Practical Quantum Computing Closer to Reality - Motherboard - June 3rd, 2017
- Team develops first blockchain that can't be hacked by quantum computer - Siliconrepublic.com - June 3rd, 2017
- D-Wave partners with U of T to move quantum computing along - Financial Post - June 2nd, 2017
- Telstra just wants a quantum computer to offer as-a-service - ZDNet - June 1st, 2017
- Microsoft, Purdue Tackle Topological Quantum Computer - HPCwire - HPCwire (blog) - June 1st, 2017
- MIT Just Unveiled A Technique to Mass Produce Quantum Computers - Futurism - June 1st, 2017
- Here's How We Can Achieve Mass-Produced Quantum Computers - ScienceAlert - June 1st, 2017
- Research collaborative pursues advanced quantum computing - Phys.Org - June 1st, 2017
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- Scientists claim to have invented the world's first quantum-proof ... - ScienceAlert - June 1st, 2017
- Google Plans to Demonstrate the Supremacy of Quantum ... - IEEE Spectrum - May 25th, 2017
- Top 5: Things to know about quantum computers - TechRepublic - May 25th, 2017
- Is the US falling behind in the race for quantum computing? - AroundtheO - May 25th, 2017
- Artificial intelligence and quantum computing aid cyber crime fight - Financial Times - May 25th, 2017