New quantum computer control electronics boost performance while lowering costs | Technology
|New quantum computer control electronics boost performance while lowering costs|
Quantum computers now have new control electronics that boost performance while lowering costs
Bridging the communication gap between the classical and quantum worlds is a significant challenge for constructing a next-generation quantum computer. To translate back and forth between the human operator and the quantum computer's languages, such computers require specialised control and readout circuitry, but current methods are inefficient and costly.
However, engineers at the US Department of Energy's Fermi National Accelerator Laboratory developed a new system of control and readout electronics known as the Quantum Instrumentation Control Kit, or QICK, which has significantly improved quantum computer performance while lowering control equipment costs.
"The Quantum Instrumentation Control Kit is an excellent example of the United States' investment in joint quantum technology research through partnerships between industry, academic institutions, and government to accelerate pre-competitive quantum research & development technologies," said Harriet Kung, DOE deputy director for science programmes as well as acting associate director of science for high-energy physics.
The team of Fermilab engineers led by senior principle engineer Gustavo Cancelo worked with the University of Chicago to design as well as evaluate a field-programmable gate array-based (FPGA) controller for quantum computing investigations. A physicist at the University of Chicago, David Schuster, oversaw the university's lab that assisted with the design and verification of real-world systems.
"This should be the kind of initiative that brings together the strengths of a national laboratory as well as a university," Schuster said. "There is a definite demand for an open-source control hardware environment, as well as the quantum community is quickly adopting it."
Engineers working on quantum computers have the difficult task of connecting the worlds of quantum as well as classical computers, which appear to be irreconcilable. Quantum computers are based on quantum physics' counterintuitive, probabilistic laws that govern the tiny universe, allowing them to execute computations that regular computers cannot. Control and readout electronics serve as the translator between these two realms since people dwell in the macroscopic visible world where classical physics dominates.
Readout electronics monitor the states of the qubits and send that information back to the classical world, while control electronics use signals from the classical world as instructions for the computer's quantum bits, or qubits.
Superconducting circuits are used as qubits in one prospective quantum computing method. Most superconducting quantum computer control and readout systems now employ off-the-shelf commercial equipment that isn't tailored for the job. As a result, researchers are frequently required to connect a dozen or more costly components. The cost per qubit can soon reach tens of thousands of dollars, and the vast scale of these systems adds to the complexity.
Despite recent technical advancements, qubits have a short lifetime, usually a fraction of a millisecond, after which they cause mistakes. "When it comes to working with qubits, time is of the essence. The response time of traditional circuits to qubits is slow, limiting the computer's capability "Cancelo remarked.
The success of a control and readout system is determined by its turnaround time, much as the effectiveness of an interpreter is determined by speedy communication. A huge system with a lot of modules also guarantees significant turnaround times.
Cancelo and his Fermilab team devised a compact control as well as readout system to overcome this problem. This single electronics board, barely bigger than a laptop, houses the capability of a complete rack of equipment. This new technology is specialised, yet it is adaptable enough to work with a variety of superconducting qubit designs.
"We're working on a generic instrument for a wide range of qubits, with the goal of covering those that will be created in the next six months or a year," Cancelo added. "You can get functionality and performance with our control and readout electronics that is difficult or impossible to achieve with commercial equipment."
Microwave pulses—radio waves with frequency comparable to those used to conduct mobile phone calls as well as heat microwave dinners—are used to control and readout qubits. The Fermilab team's radio frequency (RF) board has over 200 components, including mixers to adjust frequencies, filters to eliminate unwanted frequencies, amplifiers and attenuators to adjust signal amplitude, and switches to turn signals on and off. The low-frequency control is also included on the circuit to tweak specific qubit characteristics. The RF board, when combined with a commercial field-programmable gate array, or FPGA, board, which acts as the computer's "brains," gives scientists everything they need to connect successfully with the quantum realm.
The two small boards are around ten times less expensive to manufacture than traditional systems. They can control eight qubits in their most basic arrangement. All of the RF components are integrated into one board, allowing for quicker, more precise operation, and also real-time feedback and error correction.
"You have to inject signals that are very, extremely quick as well as very, extremely small," said team member Fermilab engineer Leandro Stefanazzi. "If you don't properly regulate the frequency and length of these signals, your qubit won't perform as you want."
The RF board as well as layout took approximately six months to design and provided significant challenges: neighbouring circuit parts had to match exactly so that signals could move smoothly without bouncing as well as clashing with one another. In addition, the engineers had to avoid using layouts that might pick up stray radio signals from sources like as cell phones and WiFi. They did simulations along the way to ensure they were on the correct route.
This design is now ready for fabrication and assembly, as well as it will be used to create RF boards this summer.
The Fermilab engineers put their ideas to the test with the University of Chicago throughout the process. Researchers like Schuster may use the new RF board to achieve significant improvements in quantum computing by combining a range of quantum computer topologies and components.
"I frequently joke that this one board has the potential to replace practically all of the test equipment in my lab," Schuster said. "It's tremendously exciting for us to collaborate with individuals who can make electronics function at that level."
This new system is scalability-friendly. Qubit controls might be frequency multiplexed, similar to delivering numerous phone calls over the same wire, allowing a single RF card to operate up to 80 qubits. Many hundred boards might be joined together and synced to the same clock as part of bigger quantum computers because of their tiny size. Cancelo and his colleagues recently published a piece in the AIP Review of Scientific Instruments describing their novel approach.
The Fermilab technical team used a new commercial FPGA chip that was the first to combine digital-to-analog as well as analog-to-digital converters directly onto the board. It drastically reduces the time it takes to create the interface between the FPGA and the RF boards, which would otherwise take months. The team has begun designing its FPGA hardware in order to improve future iterations of its control and readout system.
QuantISED, the Quantum Science Center (QSC), and eventually the Fermilab-hosted Superconducting Quantum Materials and Systems Center all contributed to the creation of QICK (SQMS). The QICK electronics are critical for research at the SQMS, where scientists are working on long-lived superconducting qubits. It's also of importance to the QSC sponsored by Oak Ridge National Laboratory, a second national quantum centre in which Fermilab plays a vital role.
A low-cost version of the hardware is currently offered only for educational applications at universities. "Because of its inexpensive cost, it enables smaller institutions to have robust quantum control without having to pay hundreds of thousands of dollars," Cancelo explained.
"From a scientific standpoint, we are working on one of the decade's hottest subjects in physics as an opportunity," he added. "What I like about this project from an engineering standpoint is that it requires many different aspects of electronic engineering to come together in order to do it properly."
Source: Tracy Marc, Fermi National Accelerator Laboratory, Phys Org, Direct News 99