Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New controls scale quantum chips

05.02.2018

A fundamental barrier to scaling quantum computing machines is "qubit interference." In new research published in Science Advances magazine, engineers and physicists from Rigetti Computing describe a breakthrough that can expand the size of practical quantum processors by reducing interference.

Matt Reagor, lead author of the paper, says: "We've developed a technique that enables us to reduce interference between qubits as we add more and more qubits to a chip, thus retaining the ability to perform logical operations that are independent of the state of a (large) quantum register."


This is Rigetti's 19Q superconducting quantum processor.

Credit: Rigetti Computing

To explain the concept, the Rigetti team employs wine glasses as an analogy to qubits:

Clink a wine glass, and you will hear it ring at its resonant frequency (usually around 400 Hz). Likewise, soundwaves at that frequency will cause the same glass to vibrate. Different shapes or amounts of liquid in a glass will produce different clinks, i.e. different resonance frequencies. A clinked wine glass will cause identical, nearby glasses to vibrate. Glasses that are different shapes are "off-resonant glasses," meaning they will not vibrate much at all.

So, what's the relation between glasses and qubits?

Reagor explains that each physical qubit on a superconducting quantum processor stores energy in the form of an oscillating electric current. "Think of each qubit as a wine glass," he says. "The logical state of a qubit (e.g. "0" or "1") is encoded by the state of its corresponding electric currents. In our analogy, this is equivalent to whether or not a wine glass is vibrating."

A highly successful class of entangling gates for superconducting qubits operate by tuning two or more qubits into resonance with each other. At this tuning point, the "wine glasses" pick up on one another's "vibrations."

This effect can be strong enough to produce significant, conditional vibration changes that can be leveraged as conditional logic. Imagine pouring or siphoning off wine from one of the glasses to make this tuning happen. With qubits, there are tunable circuit elements that fulfill the same purpose.

"As we scale up quantum processors, there are more and more wine glasses to manage when executing a specific conditional logic gate," says Reagor. "Imagine lining up a handful of identical glasses with increasing amounts of wine. Now we want to tune one glass into resonance with another, without disturbing any of the other glasses. To do that, you could try to equalize the wine levels of the glasses. But that transfer needs to be instantaneous to not shake the rest of the glasses along the way. Let's say one glass has a resonance at one frequency (call it 400 Hz) while another, nearby glass has a different one (e.g. 380 Hz). Now, we make use of a somewhat subtle musical effect. We are actually going to fill and deplete one of the glasses repeatedly."

He continues: "We repeat that filling operation at the difference frequency between the glasses (here, 20 times per second, or 20 Hz). By doing so, we create a beat-note for this glass that is exactly resonant with the other. Physicists sometimes call this a parametric process. Our beat-note is "pure" -- it does not have frequency content that interferes with the other glasses. That's what we have demonstrated in our recent work, where we navigated a complex eight-qubit processor with parametric two-qubit gates."

Reagor concludes: "While this analogy may sound somewhat fanciful, its mapping onto our specific technology, from a mathematical standpoint, is surprisingly accurate."

###

Note to editors: The full citation for this paper is: "Demonstration of Universal Parametric Entangling Gates on a Multi-Qubit Lattice, Science Advances

Media Contact

Calisa Cole
press@rigetti.com
408-218-2361

 @rigetti

http://www.rigetti.com 

Calisa Cole | EurekAlert!
Further information:
http://dx.doi.org/10.1126/sciadv.aao3603

More articles from Information Technology:

nachricht Quantum bugs, meet your new swatter
20.08.2018 | Rice University

nachricht Metamolds: Molding a mold
20.08.2018 | Institute of Science and Technology Austria

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Air pollution leads to cardiovascular diseases

21.08.2018 | Ecology, The Environment and Conservation

Researchers target protein that protects bacteria's DNA 'recipes'

21.08.2018 | Life Sciences

A paper battery powered by bacteria

21.08.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>