New control electronics for quantum computers that improve performance, cut costs

The communication gap between the classical and quantum worlds is a large problem when designing a quantum computer. Existing systems are cumbersome and expensive and need a specialized control and readout electronics to translate between the human operator and the quantum computer.

The QICK, developed by engineers at the U.S. Department of Energy, has proved to improve quantum computer performance while cutting the cost of control equipment.

The development of the Quantum Instrumentation Control Kit is an 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.

The University of Chicago collaborated with a team of engineers from the Fermilab to create and test a field-Programmable gate array-based controller for quantum computing experiments. David Schuster, a physicist at the University of Chicago, led the lab that helped with the specifications and verification on real hardware.

Schuster said that the project combines the strengths of a national laboratory and a university.

Engineers designing quantum computers have to bridge the worlds of quantum and classical computers. The counterintuitive, probabilistic rules of quantum mechanics allow quantum computers to perform calculations that ordinary computers cannot. Control and readout electronics act as the interpreter between the two worlds because people live in a world where classical physics reigns.

Control electronics use signals from the classical world as instructions for the computer's quantum bits, while readout electronics measure the states of the qubits and convey that information back to the classical world.

One promising technology for quantum computers uses qubits. Most control and readout systems for quantum computers use off-the-shelf commercial equipment. Researchers often have to string together a dozen or more expensive components. The cost can quickly add up to tens of thousands of dollars per qubit, and the large size of these systems creates more problems.

Despite recent technological advances, qubits still have a relatively short lifetime. Cancelo said that classical electronics take time to respond to the qubits, limiting the performance of the computer.

The effectiveness of a control and readout system depends on the time it takes to get there. A large system made of many modules can take a long time to complete.

Cancelo and his team at Fermilab designed a compact control and readout system to address this issue. The capabilities of an entire rack of equipment in a single electronics board is slightly larger than a laptop. The new system can be used with many different designs of qubits.

Cancelo said that they are designing a general instrument for a large variety of qubits, hoping to cover those that will be designed six months or a year from now.

Radio waves at frequencies similar to the signals that carry mobile phone calls and heat up microwave dinners control the control and readout of qubits. There are more than 200 elements in the RF board of the Fermilab team. The board has a low-frequency control that can be used to tune certain qubit parameters. The RF board is used to communicate with the quantum world.

The two boards cost 10 times less to produce. They can control eight qubits in their simplest configuration. The integration of all the RF components into a single board allows for faster, more precise operation as well as real-time feedback and error correction.

"You need to inject signals that are very, very fast and very, very short," said a member of the team.

The RF board and layout had to be designed in six months so that signals wouldn't bounce and interfere with each other. The engineers had to avoid layouts that would pick up stray radio waves from sources like cell phones. They ran simulations to make sure they were on the right track.

The goal is to have RF working boards this summer, with the design ready for fabrication and assembly.

The University of Chicago was the place where the engineers tested their ideas. The new RF board is ideal for researchers like Schuster who want to make fundamental advances in quantum computing using a wide variety of quantum computer architectures and devices.

Schuster joked that the board would replace almost all of the test equipment in his lab.

The new system is easy to use. A single RF board can control up to 80 qubits, similar to sending multiple phone conversations over the same cable. Thanks to their small size, several dozen boards could be linked together and synchronized to the same clock as part of larger quantum computers. Cancelo and his colleagues wrote a paper about their new system.

The first to integrate digital-to-analog and analog-to-digital converters directly into the board have been taken advantage of by the Fermilab engineering team. It speeds up the process of creating the interface between the two boards, which would have taken months without it. The team is designing its own hardware to improve future versions of the system.

The development of QICK was supported by the Quantum Science Center and the Superconducting Quantum Materials and Systems Center. Scientists at the SQMS are working on long-lived qubits with the help of the QICK electronics. It is also of interest to a second national quantum center, which is hosted by Oak Ridge National Laboratory.

Due to its low cost, it allows smaller institutions to have powerful quantum control without spending hundreds of thousands of dollars.

One of the hottest topics in physics of the decade is being worked on, he said.

More information: Leandro Stefanazzi et al, The QICK (Quantum Instrumentation Control Kit): Readout and control for qubits and detectors, Review of Scientific Instruments (2022). DOI: 10.1063/5.0076249 Journal information: Review of Scientific Instruments Citation: New control electronics for quantum computers that improve performance, cut costs (2022, May 3) retrieved 3 May 2022 from https://phys.org/news/2022-05-electronics-quantum.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.