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In the 1960s the U.S. government funded a series of experiments developing techniques to shuttle information from one computer to another. Devices in single labs sprouted connections, then neighboring labs linked up. Soon the network had blossomed between research institutions across the country, setting down the roots of what would become the internet and transforming forever how people use information. Now, 60 years later, the Department of Energy is aiming to do it again.

The Trump administration's 2021 budget request currently under consideration by Congress proposes slashing the overall funding for scientific research by nearly 10% but boosts spending on quantum information science by about 20%, to $237 million. Of that, the DOE has requested $25 million to accelerate the development of a quantum internet. Such a network would leverage the counterintuitive behavior of nature's particles to manipulate and share information in entirely new ways, with the potential to reinvent fields including cybersecurity and material science.

Whilethetraditional internet for general useisn't going anywhere, a quantum networkwouldoffer decisive advantages for certain applications: Researchers could use it to develop drugs and materials by simulating atomic behavior onnetworked quantum computers, for instance, and financial institutions and governments would benefit from next-level cybersecurity. Many countries are pursuing quantum research programs, and with the 2021 budget proposal, the Trumpadministration seeks to ramp up thateffort.

"That level of funding will enable us to begin to develop the groundwork for sophisticated, practical and high-impact quantum networks," says David Awschalom, a quantum engineer at the University of Chicago. "It's significant and extremely important."

A quantum internet will develop in fits and starts, much like the traditional internet did and continues to do. China has already realized an early application, quantum encryption, between certain cities, but fully quantum networks spanning entire countries will take decades, experts say. Building it willrequire re-engineering the quantum equivalent of routers, hard drives, and computers from the ground up foundational work already under way today.

Where the modern internet traffics in bits streaming between classical computers (a category that now includes smart phones, tablets, speakers and thermostats), a quantum internet would carry a fundamentally different unit of information known as the quantum bit, or qubit.

Bits all boil down to instances of nature's simplest eventsquestions with yes or no answers. Computer chips process cat videos by stopping some electric currents while letting others flow. Hard drives store documents by locking magnets in either the up or down position.

Qubits represent a different language altogether, one based on the behavior of atoms, electrons, and other particles, objects governed by the bizarre rules of quantum mechanics. These objects lead more fluid and uncertain lives than their strait-laced counterparts in classical computing. A hard drive magnet must always point up or down, for instance, but an electron's direction is unknowable until measured. More precisely, the electron behaves in such a way that describing its orientation requires a more complex concept known as superposition that goes beyond the straightforward labels of "up" or "down."

Quantum particles can also be yoked together in a relationship called entanglement, such as when two photons (light particles) shine from the same source. Pairs of entangled particles share an intimate bond akin to the relationship between the two faces of a coin when one face shows heads the other displays tails. Unlike a coin, however, entangled particles can travel far from each other and maintain their connection.

Quantum information science unites these and other phenomena, promising a novel, richer way to process information analogous to moving from 2-D to 3-D graphics, or learning to calculate with decimals instead of just whole numbers. Quantum devices fluent in nature's native tongue could, for instance, supercharge scientists' ability to design materials and drugs by emulating new atomic structures without having to test their properties in the lab. Entanglement, a delicate link destroyed by external tampering, could guarantee that connections between devices remain private.

But such miracles remain years to decades away. Both superposition and entanglement are fragile states most easily maintained at frigid temperatures in machines kept perfectly isolated from the chaos of the outside world. And as quantum computer scientists search for ways to extend their control over greater numbers of finicky particles, quantum internet researchers are developing the technologies required to link those collections of particles together.

The interior of a quantum computer prototype developed by IBM. While various groups race to build quantum computers, Department of Energy researchers seek ways to link them together.

IBM

Just as it did in the 1960s, the DOE is again sowing the seeds for a future network at its national labs. Beneath the suburbs of western Chicago lie 52 miles of optical fiber extending in two loops from Argonne National Laboratory. Early this year, Awschalom oversaw the system's first successful experiments. "We created entangled states of light," he says, "and tried to use that as a vehicle to test how entanglement works in the real world not in a lab going underneath the tollways of Illinois."

Daily temperature swings cause the wires to shrink by dozens of feet, for instance, requiring careful adjustment in the timing of the pulses to compensate. This summer the team plans to extend their network with another node, bringing the neighboring Fermi National Accelerator Laboratory into the quantum fold.

Similar experiments are under way on the East Coast, too, where researchers have sent entangled photons over fiber-optic cables connecting Brookhaven National Laboratory in New York with Stony Brook University, a distance of about 11 miles. Brookhaven scientists are also testing the wireless transmission of entangled photons over a similar distance through the air. While this technique requires fair weather, according to Kerstin Kleese van Dam, the director of Brookhaven's computational science initiative, it could someday complement networks of fiber-optic cables. "We just want to keep our options open," she says.

Such sending and receiving of entangled photons represent the equivalent of quantum routers, but next researchers need a quantum hard drive a way to save the information they're exchanging. "What we're on the cusp of doing," Kleese van Dam says, "is entangled memories over miles."

When photons carry information in from the network, quantum memory will store those qubits in the form of entangled atoms, much as current hard drives use flipped magnets to hold bits. Awschalom expects the Argonne and University of Chicago groups to have working quantum memories this summer, around the same time they expand their network to Fermilab, at which point it will span 100 miles.

But that's about as far as light can travel before growing too dim to read. Before they can grow their networks any larger, researchers will need to invent a quantum repeater a device that boosts an atrophied signal for another 100-mile journey. Classical internet repeaters just copy the information and send out a new pulse of light, but that process breaks entanglement (a feature that makes quantum communications secure from eavesdroppers). Instead, Awschalom says, researchers have come up with a scheme to amplify the quantum signal by shuffling it into other forms without ever reading it directly. "We have some prototype quantum repeaters currently running. They're not good enough," he says, "but we're learning a lot."

Department of Energy Under Secretary for Science Paul M. Dabbar (left) sends a pair of entangled photons along the quantum loop. Also shown are Argonne scientist David Awschalom (center) and Argonne Laboratory Director Paul Kearns.

Argonne National Laboratory

And if Congress approves the quantum information science line in the 2021 budget, researchers like Awschalom and Kleese van Dam will learn a lot more. Additional funding for their experiments could lay the foundations for someday extending their local links into a country-wide network. "There's a long-term vision to connect all the national labs, coast to coast," says Paul Dabbar, the DOE's Under Secretary for Science.

In some senses the U.S. trails other countries in quantum networking. China, for example, has completed a 1,200-mile backbone linking Beijing and Shanghai that banks and other companies are already using for nearly perfectly secure encryption. But the race for a fully featured quantum internet is more marathon than sprint, and China has passed only the first milestone. Kleese van Dam points out that without quantum repeaters, this network relies on a few dozen "trusted" nodes Achilles' heels that temporarily put the quantum magic on pause while the qubits are shoved through bit-based bottlenecks. She's holding out for truly secure end-to-end communication. "What we're planning to do goes way beyond what China is doing," she says.

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Researchers ultimately envision a whole quantum ecosystem of computers, memories, and repeaters all speaking the same language of superposition and entanglement, with nary a bit in sight. "It's like a big stew where everything has to be kept quantum mechanical," Awschalom says. "You don't want to go to the classical world at all."

After immediate applications such as unbreakable encryptions, he speculates that such a network could also lead to seismic sensors capable of logging the vibration of the planet at the atomic level, but says that the biggest consequences will likely be the ones no one sees coming. He compares the current state of the field to when electrical engineers developed the first transistors and initially used them to improve hearing aids, completely unaware that they were setting off down a path that would someday bring social media and video conferencing.

As researchers at Brookhaven, Argonne, and many other institutions tinker with the quantum equivalent of transistors, but they can't help but wonder what the quantum analog of video chat will be. "It's clear there's a lot of promise. It's going to move quickly," Awschalom says. "But the most exciting part is that we don't know exactly where it's going to go."

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Trump betting millions to lay the groundwork for quantum internet in the US - CNBC

The basic units of a quantum computer can be rearranged in 2D to solve typical design and operation challenges. Efficient quantum computing is expected to enable advancements that are impossible with classical computers. A group of scientists from Tokyo University of Science, Japan, RIKEN Centre for Emergent Matter Science, Japan, and the University of Technology, Sydney have collaborated and proposed a novel two-dimensional design that can be constructed using existing integrated circuit technology. This design solves typical problems facing the current three-dimensional packaging for scaled-up quantum computers, bringing the future one step closer.

Quantum computing is increasingly becoming the focus of scientists in fields such as physics and chemistry, and industrialists in the pharmaceutical, airplane, and automobile industries. Globally, research labs at companies like Google and IBM are spending extensive resources on improving quantum computers, and with good reason. Quantum computers use the fundamentals of quantum mechanics to process significantly greater amounts of information much faster than classical computers. It is expected that when the error-corrected and fault-tolerant quantum computation is achieved, scientific and technological advancement will occur at an unprecedented scale.

But, building quantum computers for large-scale computation is proving to be a challenge in terms of their architecture. The basic units of a quantum computer are the quantum bits or qubits. These are typically atoms, ions, photons, subatomic particles such as electrons, or even larger elements that simultaneously exist in multiple states, making it possible to obtain several potential outcomes rapidly for large volumes of data. The theoretical requirement for quantum computers is that these are arranged in two-dimensional (2D) arrays, where each qubit is both coupled with its nearest neighbor and connected to the necessary external control lines and devices. When the number of qubits in an array is increased, it becomes difficult to reach qubits in the interior of the array from the edge. The need to solve this problem has so far resulted in complex three-dimensional (3D) wiring systems across multiple planes in which many wires intersect, making their construction a significant engineering challenge. https://youtu.be/14a__swsYSU

The team of scientists led by Prof Jaw-Shen Tsai has proposed a unique solution to this qubit accessibility problem by modifying the architecture of the qubit array. Here, we solve this problem and present a modified superconducting micro-architecture that does not require any 3D external line technology and reverts to a completely planar design, they say. This study has been published in the New Journal of Physics.

The scientists began with a qubit square lattice array and stretched out each column in the 2D plane. They then folded each successive column on top of each other, forming a dual one-dimensional array called a bi-linear array. This put all qubits on the edge and simplified the arrangement of the required wiring system. The system is also completely in 2D. In this new architecture, some of the inter-qubit wiringeach qubit is also connected to all adjacent qubits in an arraydoes overlap, but because these are the only overlaps in the wiring, simple local 3D systems such as airbridges at the point of overlap are enough and the system overall remains in 2D. As you can imagine, this simplifies its construction considerably.

The scientists evaluated the feasibility of this new arrangement through numerical and experimental evaluation in which they tested how much of a signal was retained before and after it passed through an airbridge. The results of both evaluations showed that it is possible to build and run this system using existing technology and without any 3D arrangement.

The scientists experiments also showed them that their architecture solves several problems that plague the 3D structures: they are difficult to construct, there is crosstalk or signal interference between waves transmitted across two wires, and the fragile quantum states of the qubits can degrade. The novel pseudo-2D design reduces the number of times wires cross each other, thereby reducing the crosstalk and consequently increasing the efficiency of the system.

At a time when large labs worldwide are attempting to find ways to build large-scale fault-tolerant quantum computers, the findings of this exciting new study indicate that such computers can be built using existing 2D integrated circuit technology. The quantum computer is an information device expected to far exceed the capabilities of modern computers, Prof Tsai states. The research journey in this direction has only begun with this study, and Prof Tsai concludes by saying, We are planning to construct a small-scale circuit to further examine and explore the possibility.

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Wiring the Quantum Computer of the Future: Researchers from Japan and Australia propose a novel 2D design - QS WOW News