QICK Hardware Aims to Bridge Classical and Quantum Communication Gap

Over the past couple of years, quantum computing has become one of the most popular emerging technologies promising to circumvent the limitations of traditional semiconductor processors and fundamentally change the way we compute complex mathematical problems by utilizing the laws of quantum mechanics.

Quantum computers, to achieve this, use the quantum states of particles (such as spin or charge) to represent quantum bits (or qubits for short). Unlike semiconductor bits, which can be either a one or a zero (on or off), they can occupy two states simultaneously until observed or until a specific calculation is completed.

This article focuses on the control side of quantum computing with the latest development from Fermilab, which aims to cut down the cost of quantum computing infrastructures with standardized qubit control instrumentation.

 

Reading and Manipulating Qubits

While some researchers are working on different approaches to quantum computing using different methodologies with varying particles as qubits, each with its unique benefits and potential drawbacks, others are working on the crucial control electronics that enable these quantum bits to communicate with classical semiconductor machines.

 

An example quantum control system. Image used courtesy of the University of Chicago

 

Controlling and reading out the states of qubits is probably one of the most complex challenges in the development of quantum computers. This area of quantum computing can be a challenge because the process itself requires a significant infrastructure that guarantees the stability and accuracy of the system while also enabling communication between the engineers and these subatomic particles.

Although the qubits work on a quantum mechanics level, operating and measuring them is still done on our classical physics level via traditional semiconductor electronics. Currently, this is only possible using complex and proprietary quantum computing control systems (QCCSs), which can differ from one design to the next even if the design itself uses the same particles for qubits (like ion trap qubits or superconducting qubits, for example).

 

An example of a QCCS system architecture. Image used courtesy of Zurich Instruments

 

Standardizing QCCSs is one of the next steps in the development of quantum processors that could not only save time, money, and resources but will also allow for more stable quantum machines, limiting interference and improving accuracy by using specialized electronics as opposed to modifying off-the-shelf equipment that is not specialized for the task.

 

Fermilab’s Quantum Control System

Hoping to solve some of the controls of quantum computing, Fermilab, the United States Department of Energy's national laboratory, announced its QCCS for running superconducting qubits. Located in Batavia, Illinois, this institution specializes in particle physics, collaborating with experts from the industry and universities around the world.

The primary target for their new system, the superconducting qubits, is to become one of the leading candidates for developing quantum processor platforms. These platforms are where information can be stored in the quantum degrees of freedom of nanofabricated, anharmonic oscillators made out of superconducting circuit elements. 

Led by Gustavo Cancelo, in collaboration with the University of Chicago, a team of engineers from Fermilab set out to create a field-programmable gate array (FPGA) controller for their future quantum experiments. The results were a system called QICK, which is short for Quantum Instrumentation Control Kit.

 

The QICK control system board. Image used courtesy of Stefanazzi et al

 

According to the engineers, their compact control and readout board has the capabilities of an entire rack of electronic instruments fit inside a footprint slightly larger than a laptop. Hoping to solve the problem of QCCSs, while this system is specialized for certain tasks, in theory, it's supposed to be compatible with multiple different quantum computer designs. 

The QICK instrument works using microwave frequencies for controlling and reading qubits. It contains more than two hundred components designed to mix, tweak, and amplify these signals while filtering out the unnecessary frequencies and limiting outside interference.

 

The QICK stack-up. Image used courtesy of Stefanazzi et al

 

Claiming to cost about 10x less than current quantum computing control systems, QICK has the potential to control eight qubits at a time more precisely. This process includes real-time feedback and error correction as it integrates all the necessary control and readout components into one single compact circuit.

According to the team, designing and testing this board took about six months, with the production and assembly of functional boards set to start this summer. A low-cost variant of their board is currently available to universities for educational purposes.

On the coattails of this achievement, Fermilab has already made plans to improve and scale its system. Similar to how frequency multiplexing connects multiple phone lines in telecommunications, engineers can scale the QICK system to control up to eighty qubits using a single board. While doing so, it can also allow for the synchronization of multiple boards to the same clock inside a single quantum computer.

 

What QICK Means for the Future of Quantum Computing

The need for more computational power combined with the physical limitations of semiconductor processors is a significant reason why scientists and engineers are always on the lookout for new computing technologies and materials. Quantum machines often find themselves as one the leaders in this race toward a new technological revolution thanks to the promise of what they can potentially achieve in the future. 

However, while still costly and difficult, developing quantum computing hardware is becoming more accessible to a wider variety of companies, universities, and institutions thanks to these attempts at standardizing qubit communication and control systems.

Fermilab's QICK instrument could be seen as a vital sign that comes directly from a national institute in the hopes of furthering the field. Additionally, if the fundamental laws of quantum mechanics allow it, putting engineers closer to the goal of building practical quantum processors and getting them to solve real-world problems outside of the lab.