Quantum Computing News and Discussions

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weatheriscool
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Fault-tolerant quantum computer memory in diamond
https://phys.org/news/2022-04-fault-tol ... amond.html
by Yokohama National University

Quantum computing holds the potential to be a game-changing future technology in fields ranging from chemistry to cryptography to finance to pharmaceuticals. Compared to conventional computers, scientists suggest that quantum computers could operate many thousand times faster. To harness this power, scientists today are looking at ways to construct quantum computer networks. Fault-tolerant quantum memory, which responds well when hardware or software malfunctions occur, will play an important role in these networks. A research team from Yokohama National University is exploring quantum memory that is resilient against operational or environmental errors.

The research team reported their findings on April 27, 2022 in the journal Communications Physics.
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caltrek
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New Approach May Help Clear Hurdle to Large-scale Quantum Computing
April 29, 2022

https://www.eurekalert.org/news-releases/951249

Introduction:
(EurekAlert) Building a plane while flying it isn’t typically a goal for most, but for a team of Harvard-led physicists that general idea might be a key to finally building large-scale quantum computers.

Described in a new paper in Nature, the research team, which includes collaborators from QuEra Computing, MIT, and the University of Innsbruck, developed a new approach for processing quantum information that allows them to dynamically change the layout of atoms in their system by moving and connecting them with each other in the midst of computation.

This ability to shuffle the qubits (the fundamental building blocks of quantum computers and the source of their massive processing power) during the computation process while preserving their quantum state dramatically expands processing capabilities and allows for the self-correction of errors. Clearing this hurdle marks a major step toward building large-scale machines that leverage the bizarre characteristics of quantum mechanics and promise to bring about real-world breakthroughs in material science, communication technologies, finance, and many other fields.

“The reason why building large scale quantum computers is hard is because eventually you have errors,” said Mikhail Lukin, the George Vasmer Leverett Professor of Physics, co-director of the Harvard Quantum Initiative, and one of the senior authors of the study. “One way to reduce these errors is to just make your qubits better and better, but another more systematic and ultimately practical way is to do something which is called quantum error correction. That means that even if you have some errors, you can correct these errors during your computation process with redundancy.”

In classical computing, error correction is done by simply copying information from a single binary digit or bit so it’s clear when and where it failed. For example, one single bit of 0 can be copied three times to read 000. Suddenly, when it reads 001, it’s clear where the error is and can be corrected. A foundational limitation of quantum mechanics is that information can’t be copied, making error correction difficult.
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weatheriscool
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New control electronics for quantum computers that improve performance, cut costs
https://phys.org/news/2022-05-electronics-quantum.html
by Tracy Marc, Fermi National Accelerator Laboratory
When designing a next-generation quantum computer, a surprisingly large problem is bridging the communication gap between the classical and quantum worlds. Such computers need a specialized control and readout electronics to translate back and forth between the human operator and the quantum computer's languages—but existing systems are cumbersome and expensive.

However, a new system of control and readout electronics, known as Quantum Instrumentation Control Kit, or QICK, developed by engineers at the U.S. Department of Energy's Fermi National Accelerator Laboratory, has proved to drastically improve quantum computer performance while cutting the cost of control equipment.

"The development of the Quantum Instrumentation Control Kit is an excellent example of U.S. investment in joint quantum technology research with partnerships between industry, academia and government to accelerate pre-competitive quantum research and development technologies," said Harriet Kung, DOE deputy director for science programs for the Office of Science and acting associate director of science for high-energy physics.
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caltrek
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Dutch Researchers Teleport Quantum Information Across Rudimentary Quantum Network
May 25, 2022

Introduction:
(EurekAlert) Researchers in Delft have succeeded in teleporting quantum information across a rudimentary network. This first of its kind is an important step towards a future quantum Internet. This breakthrough was made possible by a greatly improved quantum memory and enhanced quality of the quantum links between the three nodes of the network. The researchers, working at QuTech—a collaboration between Delft University of Technology and the Netherlands Organisation for Applied Scientific Research (TNO)—are publishing their findings today in the scientific journal Nature.

The power of a future quantum Internet is based on the ability to send quantum information (quantum bits) between the nodes of the network. This will enable all kinds of applications such as securely sharing confidential information, linking several quantum computers together to increase their computing capability, and the use of highly precise, linked quantum sensors.

Sending quantum information

The nodes of such a quantum network consist of small quantum processors. Sending quantum information between these processors is no easy feat. One possibility is to send quantum bits using light particles but, due to the inevitable losses in glass fibre cables, in particular over long distances, the light particles will very likely not reach their destination. As it is fundamentally impossible to simply copy quantum bits, the loss of a light particle means that the quantum information is irrecoverably lost.

Teleportation offers a better way of sending quantum information. The protocol for quantum teleportation owes its name to similarities with teleportation in science-fiction films: the quantum bit disappears on the side of the sender and appears on the side of the receiver. As the quantum bit therefore does not need to travel across the intervening space, there is no chance that it will be lost. This makes quantum teleportation an crucial technique for a future quantum Internet.
Read more here: https://www.eurekalert.org/news-releases/953932

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Error-free quantum computing gets real

by University of Innsbruck
https://phys.org/news/2022-05-error-fre ... -real.html
In modern computers, errors during processing and storage of information have become a rarity due to high-quality fabrication. However, for critical applications, where even single errors can have serious effects, error correction mechanisms based on redundancy of the processed data are still used.

Quantum computers are inherently much more susceptible to disturbances and will thus probably always require error correction mechanisms, because otherwise errors will propagate uncontrolled in the system and information will be lost. Because the fundamental laws of quantum mechanics forbid copying quantum information, redundancy can be achieved by distributing logical quantum information into an entangled state of several physical systems, for example multiple individual atoms.

The team led by Thomas Monz of the Department of Experimental Physics at the University of Innsbruck and Markus Müller of RWTH Aachen University and Forschungszentrum Jülich in Germany has now succeeded for the first time in realizing a set of computational operations on two logical quantum bits that can be used to implement any possible operation. "For a real-world quantum computer, we need a universal set of gates with which we can program all algorithms," explains Lukas Postler, an experimental physicist from Innsbruck.

Fundamental quantum operation realized

The team of researchers implemented this universal gate set on an ion trap quantum computer featuring 16 trapped atoms. The quantum information was stored in two logical quantum bits, each distributed over seven atoms.
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Doubling up Cooper pairs to protect qubits in quantum computers from noise
https://phys.org/news/2022-06-cooper-pa ... noise.html
by Bob Yirka , Phys.org
A team of researchers affiliated with several institutions in France has developed a means of using pairs of Cooper pairs to protect qubits inside a quantum computer from external noise. In their paper published in the journal Physical Review X, the group describes how they tackled the problem of qubit sensitivity to noise and how well their approach worked when tested.

An obstacle to the development of quantum computers is external noise affecting qubits. One of the most promising approaches to dealing with noise is to delocalize the quantum information used in the computer. This is because the noise that creates problems is typically local. The idea is to delocalize where the information is stored, and the researchers developed a new way to do that.

Inside a quantum computer are superconducting circuits—their states can be described using pairs of electrons known as Cooper pairs. In such systems, the pairs tunnel through a Josephson junction. The researchers came up with a new kind of superconducting qubit in which the quantum states are nonlocalized by modifying the Josephson junction. In their setup, two Cooper pairs were allowed to tunnel through simultaneously. The junction was made using a superconducting loop that also made use of superinductors. Using this approach allowed the team to control the kinetic interference co-tunneling element. This resulted in suppressing the tunneling of undesired Cooper pairs, allowing those that were co-tunneling to pass through unharmed. The approach led to doubling the magnification of the superconducting phase.
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Theory suggests quantum computers should be exponentially faster on some learning tasks than classical machines
https://phys.org/news/2022-06-theory-qu ... tasks.html
by Bob Yirka , Phys.org
A team of researchers affiliated with multiple institutions in the U.S., including Google Quantum AI, and a colleague in Australia, has developed a theory suggesting that quantum computers should be exponentially faster on some learning tasks than classical machines. In their paper published in the journal Science, the group describes their theory and results when tested on Google's Sycamore quantum computer. Vedran Dunjko with Leiden University City has published a Perspective piece in the same journal issue outlining the idea behind combining quantum computing with machine learning to provide a new level of computer-based learning systems.

Machine learning is a system by which computers trained with datasets make informed guesses about new data. And quantum computing involves using sub-atomic particles to represent qubits as a means for conducting applications many times faster than is possible with classical computers. In this new effort, the researchers considered the idea of running machine-learning applications on quantum computers, possibly making them better at learning, and thus more useful.

To find out if the idea might be possible, and more importantly, if the results would be better than those achieved on classical computers, the researchers posed the problem in a novel way—they devised a machine learning task that would learn via experiments repeated many times over. They then developed theories describing how a quantum system could be used to conduct such experiments and to learn from them. They found that they were able to prove that a quantum computer could do it, and that it could do it much better than a classical system. In fact, they found a reduction in the required number of experiments needed to learn a concept to be four orders of magnitude lower than for classical systems. The researchers then built such a system and tested it on Google's Sycamore quantum computer and confirmed their theory.
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Atom Computing’s Neutral Atom Quantum Computer Sets Coherence Record
June 10, 2022 by Brian Wang
https://www.nextbigfuture.com/2022/06/a ... ecord.html

Atom Computing has closed a $60M in Series B funding, which brings their total funding to $80 million. They are building a larger second-generation quantum computing system that can run commercial use-cases.

Atom Computing’s record-setting qubit coherence was 40 seconds plus or minus 7 seconds. That may not seem very long compared to everyday life, but relative to quantum states, it is more than several lifetimes. Coherence times vary widely from a few milliseconds and up, depending on qubit type, hardware configurations, and operational procedures.

If the operations are less than a microsecond then the 40 second coherence time allows for 40 million quantum operations.
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The realization of measurement induced quantum phases on a trapped-ion quantum computer
https://phys.org/news/2022-06-quantum-p ... d-ion.html
by Ingrid Fadelli , Phys.org

Trapped-ion quantum computers are quantum devices in which trapped ions vibrate together and are fully isolated from the external environment. These computers can be particularly useful for investigating and realizing various quantum physics states.

Researchers at NIST/University of Maryland and Duke University have recently used a trapped-ion quantum computer to realize two measurement-induced quantum phases, namely the pure phase and mixed or coding phase during a purification phase transition. Their findings, published in a paper in Nature Physics, contribute to the experimental understanding of many-body quantum systems.

"Our methods were based on work by Michael Gullans and David Huse, which identified a measurement-induced purification transition in random quantum circuits," Crystal Noel, one of the researchers who carried out the study, told Phys.org. "The main objective of our paper was to observe this critical phenomenon experimentally, using a quantum computer."
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Another important milestone in quantum computing:
In “Quantum Advantage in Learning from Experiments”, a collaboration with researchers at Caltech, Harvard, Berkeley, and Microsoft published in Science, we show that a quantum learning agent can perform exponentially better than a classical learning agent at many tasks. Using Google’s quantum computer, Sycamore, we demonstrate the tremendous advantage that a quantum machine learning (QML) algorithm has over the best possible classical algorithm. Unlike previous quantum advantage demonstrations, no advances in classical computing power could overcome this gap. This is the first demonstration of a provable exponential advantage in learning about quantum systems that is robust even on today's noisy hardware.
https://ai.googleblog.com/2022/06/quant ... -from.html

BTW, here's the difference between the more-familiar "quantum supremacy" and "quantum advantage":
Quantum Supremacy: This term still retains Preskill’s original context and is considered the first major step to prove quantum computing is feasible. Specifically, it means: “demonstrating that a programmable quantum device can solve any problem that no classical computing device can solve in a feasible amount of time, irrespective of the usefulness of the problem.” Based on the definition, this threshold has been passed since October 2019, in fact at this point it has been shown by several different companies beyond Google and this is why I refer to the current hurdles as engineering challenges rather that theoretical ones.

Quantum Advantage: Refers to the demonstrated and measured success in processing a real-world problem faster on a Quantum Computer than on a classical computer. While it is generally accepted that we have achieved quantum supremacy, it is anticipated that quantum advantage is still some years away.


Note: The above quote came from an article written only seven months ago.
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