Developing a Scalable Quantum Control and Readout System

By making use of particular quantum properties, quantum computers could resolve some computational issues much faster than ordinary computers.

The fundamental building blocks of such machines are known as quantum-bits or qubits. Qubits could be realized utilizing numerous physical platforms like nuclear spins, cold atoms, trapped ions, and photons, and also using superconducting Josephson circuits.

Numerous such qubits function in the microwave frequency domain and need specialized room-temperature microwave electronics for control and readout of the quantum states of the qubits.

But there comes a difficulty when it comes to linking classical electronics to such qubits. The qubits require high-frequency (GHz) electromagnetic signals for control and readout pulses in the order of a few tens of nanoseconds.

The conventional setup for the generation and capture of such signals is frequently expensive and complicated with several components.

This could be tackled by developing a particular FPGA-based system that gets the functionality of all the conventional equipment onto a single board. But with such developments, three main difficulties need to be considered: scalability, generation, and capture of the high-fidelity microwave signals, and an easy-to-use interface.

In a new study performed, scientists from the Departments of Physics and Electronic Systems Engineering, IISc, have tackled these difficulties with the development of Scalable Quantum Control and Readout System (SQ-CARS), utilizing Xilinx RFSoC FPGA board.

The research group tested their SQ-CARS system by performing various experiments with superconducting transmon qubits and benchmarked it against the conventional setup.

SQ-CARS is quite a versatile electronics platform which has been extensively tuned up for speed, scale, complexity and cost, while measuring multi-qubit devices in the microwave domain. To the best of my knowledge, it is the first of its kind deep-tech effort from India.

Vibhor Singh, Study Author and Associate Professor, Department of Physics, Indian Institute of Science

With the help of SQ-CARS, scientists have come up with an easy-to-use and scalable platform for physicists to perform advanced quantum experiments at a fractional cost (over 10x reduction in the cost) and a huge reduction concerning size.

The core challenge in practical quantum computer development is integrating a large number of qubits with control and readout electronics. This work lays the foundation for scalable indigenous quantum processors.

Chetan Singh Thakur, Study Author and Associate Professor, Department of Electronic Systems Engineering, Indian Institute of Science

Journal Reference

Singhal, U., et al. (2023) SQ-CARS: A Scalable Quantum Control and Readout System. IEEE Xplore. doi.org/10.1109/TIM.2023.3305656.