Nav: Home

New, better way to build circuits for world's first useful quantum computers

June 27, 2016

The era of quantum computers is one step closer as a result of research published in the current issue of the journal Science. The research team has devised and demonstrated a new way to pack a lot more quantum computing power into a much smaller space and with much greater control than ever before. The research advance, using a 3-dimensional array of atoms in quantum states called quantum bits -- or qubits -- was made by David S. Weiss, professor of physics at Penn State University, and three students on his lab team. He said "Our result is one of the many important developments that still are needed on the way to achieving quantum computers that will be useful for doing computations that are impossible to do today, with applications in cryptography for electronic data security and other computing-intensive fields."

The new technique uses both laser light and microwaves to precisely control the switching of selected individual qubits from one quantum state to another without altering the states of the other atoms in the cubic array. The new technique demonstrates the potential use of atoms as the building blocks of circuits in future quantum computers.

The scientists invented an innovative way to arrange and precisely control the qubits, which are necessary for doing calculations in a quantum computer. "Our paper demonstrates that this novel approach is a precise, accurate, and efficient way to control large ensembles of qubits for quantum computing," Weiss said.

The paper in Science describes the new technique, which Weiss's team plans to continue developing further. The achievement also is expected to be useful to scientists pursuing other approaches to building a quantum computer, including those based on other atoms, on ions, or on atom-like systems in 1 or 2 dimensions. "If this technique is adopted in those other geometries, they would also get this robustness," Weiss said.

To corral their quantum atoms into an orderly 3-D pattern for their experiments, the team constructed a lattice made by beams of light to trap and hold the atoms in a cubic arrangement of five stacked planes -- like a sandwich made with five slices of bread -- each with room for 25 equally spaced atoms. The arrangement forms a cube with an orderly pattern of individual locations for 125 atoms. The scientists filled some of the possible locations with qubits consisting of neutral cesium atoms -- those without a positive or a negative charge. Unlike the bits in a classical computer, which typically are either zeros or ones, each of the qubits in the Weiss team's experiment has the difficult-to-imagine ability to be in more than one state at the same time -- a central feature of quantum mechanics called quantum superposition.

Weiss and his team then use another kind of light tool -- crossed beams of laser light -- to target individual atoms in the lattice. The focus of these two laser beams, called "addressing" beams, on a targeted atom shifts some of that atom's energy levels by about twice as much as it does for those of any of the other atoms in the array, including those that were in the path of one of the addressing beams on its way to the target. When the scientists then bathe the whole array with a uniform wash of microwaves, the state of the atom with the shifted energy levels is changed, while the states of all the other atoms are not.

"We have set more qubits into different, precise quantum superpositions at the same time than in any previous experimental system," Weiss said. The scientists also designed their system to be very insensitive to the exact details of the alignments or the power of those light beams they use -- which Weiss said is a good thing because "you don't want to be dependent upon exactly what the intensity of the light is or exactly what the alignment is."

One of the ways that the scientists demonstrated their ability to change the quantum state of individual atoms was by changing the states of selected atoms in three of the stacked planes within the cubic array in order to draw the letters P, S, and U -- the letters that represent Penn State University. "We changed the quantum superposition of the PSU atoms to be different from the quantum superposition of the other atoms in the array," Weiss said. "We have a pretty high-fidelity system. We can do targeted selections with a reliability of about 99.7%, and we have a plan for making that more like 99.99%."

Among the goals that Weiss has for his team's future research is to get the qubits to "have entangled quantum wave functions where the state of one particle is implicitly correlated with the state of the other particles around it." Weiss said that this entangled connection between qubits is a critical element needed for quantum computing. He said he hopes that building on the techniques demonstrated in his team's prototype system eventually will enable his lab to demonstrate high-quality entangling operations for quantum computing. "Filling the cube with exactly one atom per site and setting up entanglements between atoms at any of the sites that we choose are among our nearer-term research goals," Weiss said.
In addition to Weiss, the other members of the Penn State research team are Yang Wang, Aishwarya Kumar, and Tsung-Yao Wu, all graduate students. The research was funded by the U.S. National Science Foundation.


David Weiss:, (+1) 814-863-3076
Barbara Kennedy (PIO):, (+1) 814-863-4682

Penn State

Related Quantum Computing Articles:

New method could enable more stable and scalable quantum computing, Penn physicists report
Researchers from the University of Pennsylvania, in collaboration with Johns Hopkins University and Goucher College, have discovered a new topological material which may enable fault-tolerant quantum computing.
Stanford team brings quantum computing closer to reality with new materials
Quantum computing could outsmart current computing for complex problem solving, but only if scientists figure out how to make it practical.
Computing -- quantum deep
In a first for deep learning, an Oak Ridge National Laboratory-led team is bringing together quantum, high-performance and neuromorphic computing architectures to address complex issues that, if resolved, could clear the way for more flexible, efficient technologies in intelligent computing.
Legacy of brilliant young scientist is a major leap in quantum computing
Researchers from the University of Bristol and Université Libre de Bruxelles have theoretically shown how to write programs for random circuitry in quantum computers.
WSU mathematician breaks down how to defend against quantum computing attacks
WSU mathematician Nathan Hamlin is the author of a new paper that explains how a code he wrote for a doctoral thesis, the Generalized Knapsack Code, could thwart hackers armed with next generation quantum computers.
Protecting quantum computing networks against hacking threats
As we saw during the 2016 US election, protecting traditional computer systems, which use zeros and ones, from hackers is not a perfect science.
Electron-photon small-talk could have big impact on quantum computing
In a step that brings silicon-based quantum computers closer to reality, researchers at Princeton University have built a device in which a single electron can pass its quantum information to a particle of light.
Bridging the advances in AI and quantum computing for drug discovery and longevity research
Insilico Medicine Inc. and YMK Photonics Inc. announced a research collaboration and business cooperation to develop photonics quantum computing and accelerated deep learning techniques for drug discovery, biomarker development and aging research.
New technique for creating NV-doped nanodiamonds may be boost for quantum computing
Researchers at North Carolina State University have developed a new technique for creating NV-doped single-crystal nanodiamonds, only four to eight nanometers wide, which could serve as components in room-temperature quantum computing technologies.
Exploring defects in nanoscale devices for possible quantum computing applications
Researchers at Tokyo Institute of Technology in collaboration with the University of Cambridge have studied the interaction between microwave fields and electronic defect states inside the oxide layer of field-effect transistors at cryogenic temperatures.

Related Quantum Computing Reading:

Quantum Computing: A Gentle Introduction (Scientific and Engineering Computation)
by Eleanor G. Rieffel (Author), Wolfgang H. Polak (Author)

A thorough exposition of quantum computing and the underlying concepts of quantum physics, with explanations of the relevant mathematics and numerous examples.

The combination of two of the twentieth century's most influential and revolutionary scientific theories, information theory and quantum mechanics, gave rise to a radically new view of computing and information. Quantum information processing explores the implications of using quantum mechanics instead of classical mechanics to model information and its processing. Quantum computing is not about changing the physical... View Details

Quantum Computing since Democritus
by Scott Aaronson (Author)

Written by noted quantum computing theorist Scott Aaronson, this book takes readers on a tour through some of the deepest ideas of maths, computer science and physics. Full of insights, arguments and philosophical perspectives, the book covers an amazing array of topics. Beginning in antiquity with Democritus, it progresses through logic and set theory, computability and complexity theory, quantum computing, cryptography, the information content of quantum states and the interpretation of quantum mechanics. There are also extended discussions about time travel, Newcomb's Paradox, the... View Details

An Overview of Quantum Computing: " The State of The Art In Computers "
by Edited by Paul F. Kisak (Author)

Quantum computing uses the phenomena of quantum mechanics to perform it’s calculations. The computational speed would be orders of magnitude greater than present day digital computers that we have become used to using whether it be a large scale mainframe or a desktop, laptop, tablet or phone. The digital computer uses bits which are a binary form of utilizing information in one of two states – either a 1 or a 0. The quantum computer uses quantum bits or qbits which can utilize data in a variety of states due to the quantum mechanical principles of superposition and entanglement. These... View Details

Quantum Computing for Computer Scientists
by Noson S. Yanofsky (Author), Mirco A. Mannucci (Author)

The multidisciplinary field of quantum computing strives to exploit some of the uncanny aspects of quantum mechanics to expand our computational horizons. Quantum Computing for Computer Scientists takes readers on a tour of this fascinating area of cutting-edge research. Written in an accessible yet rigorous fashion, this book employs ideas and techniques familiar to every student of computer science. The reader is not expected to have any advanced mathematics or physics background. After presenting the necessary prerequisites, the material is organized to look at different aspects of quantum... View Details

Quantum Computation and Quantum Information: 10th Anniversary Edition
by Michael A. Nielsen (Author), Isaac L. Chuang (Author)

One of the most cited books in physics of all time, Quantum Computation and Quantum Information remains the best textbook in this exciting field of science. This 10th anniversary edition includes an introduction from the authors setting the work in context. This comprehensive textbook describes such remarkable effects as fast quantum algorithms, quantum teleportation, quantum cryptography and quantum error-correction. Quantum mechanics and computer science are introduced before moving on to describe what a quantum computer is, how it can be used to solve problems faster than 'classical'... View Details

Quantum Mechanics: The Theoretical Minimum
by Leonard Susskind (Author), Art Friedman (Author)

From the bestselling author of The Theoretical Minimum, a DIY introduction to the math and science of quantum mechanics.
First he taught you classical mechanics. Now, physicist Leonard Susskind has teamed up with data engineer Art Friedman to present the theory and associated mathematics of the strange world of quantum mechanics.

In this follow-up to the New York Times best-selling The Theoretical Minimum, Susskind and Friedman provide a lively introduction to this famously difficult field, which attempts to understand the behavior of sub-atomic objects... View Details

Quantum Computing from the Ground Up
by Riley Tipton Perry (Author)

Quantum computing - the application of quantum mechanics to information - represents a fundamental break from classical information and promises to dramatically increase a computer's power. Many difficult problems, such as the factorization of large numbers, have so far resisted attack by classical computers yet are easily solved with quantum computers. If they become feasible, quantum computers will end standard practices such as Rsa encryption. Most of the books or papers on quantum computing require (or assume) prior knowledge of certain areas such as linear algebra or quantum mechanics.... View Details

Quantum Computer Science: An Introduction
by N. David Mermin (Author)

In the 1990's it was realized that quantum physics has some spectacular applications in computer science. This book is a concise introduction to quantum computation, developing the basic elements of this new branch of computational theory without assuming any background in physics. It begins with an introduction to the quantum theory from a computer-science perspective. It illustrates the quantum-computational approach with several elementary examples of quantum speed-up, before moving to the major applications: Shor's factoring algorithm, Grover's search algorithm, and quantum error... View Details

An Introduction to Quantum Computing
by Phillip Kaye (Author), Raymond Laflamme (Author), Michele Mosca (Author)

This concise, accessible text provides a thorough introduction to quantum computing - an exciting emergent field at the interface of the computer, engineering, mathematical and physical sciences. Aimed at advanced undergraduate and beginning graduate students in these disciplines, the text is technically detailed and is clearly illustrated throughout with diagrams and exercises. Some prior knowledge of linear algebra is assumed, including vector spaces and inner products. However, prior familiarity with topics such as tensor products and spectral decomposition is not required, as the... View Details

Computing with Quantum Cats: From Colossus to Qubits
by John Gribbin (Author)

A mind-blowing glimpse into the near future, where quantum computing will have world-transforming effects.

The quantum computer is no longer the stuff of science fiction. Pioneering physicists are on the brink of unlocking a new quantum universe which provides a better representation of reality than our everyday experiences and common sense ever could. The birth of quantum computers - which, like Schrödinger's famous "dead and alive" cat, rely on entities like electrons, photons, or atoms existing in two states at the same time - is set to turn the computing world on its... View Details

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

The Big Five
What are the five biggest global challenges we face right now — and what can we do about them? This hour, TED speakers explore some radical solutions to these enduring problems. Guests include geoengineer Tim Kruger, president of the International Rescue Committee David Miliband, political scientist Ian Bremmer, global data analyst Sarah Menker, and historian Rutger Bregman.
Now Playing: Science for the People

#456 Inside a Conservation NGO
This week we take a close look at conservation NGOS: what they do, how they work, and - most importantly - why we need them. We'll be speaking with Shyla Raghav, the Climate Change Lead at Conservation International, about using strategy and policy to tackle climate change. Then we'll speak with Rebecca Shaw, Lead Scientist at the World Wildlife Fund, about how and why you should get involved with conservation initiatives.