Josephson Microwave Sources Applied to Quantum Information Systems

Adam J. Sirois,Peter F. Hopkins,Manuel Castellanos-Beltran,Samuel P. Benz,Anna E. Fox

doi:10.1109/tqe.2020.3045682

Abstract

Quantum computers with thousands or millions of qubits will require a scalable solution for qubit control and readout electronics. Colocating these electronics at millikelvin temperatures has been proposed and demonstrated, but there exist significant challenges with power dissipation, reproducibility, fidelity, and scalability. In this article, we experimentally demonstrate the use of a Josephson arbitrary waveform synthesizer (JAWS) to generate control signals at 4 K and perform spectroscopy of two components of a typical superconducting quantum information system: a linear resonator and a (nonlinear) transmon qubit. By locating the JAWS chip at 4 K and a qubit at 0.1 K, the direct path for quasi-particle poisoning from the JAWS chip to the qubit is broken. We demonstrate the stable, self-calibrated, and reproducible output signal of the JAWS when operated in its quantum locking range, a feature that allows these synthesizers to be replicated and scaled in the cryostat, all with identical on-chip, quantized, outputs. This is a proof-of-concept demonstration to generate signals at 4 K using driven superconducting electronics to control qubits at lower temperatures.

Highlights

Superconducting circuit quantum electrodynamics experiments form the basis for many quantum computing technologies [1]–[3]
Josephson junctions (JJs)-based digital logic elements—generally referred to here as single flux quantum (SFQ) electronics—have been proposed and initial demonstrations have shown them to be a potential solution to scaling quantum computing technologies to larger numbers of qubits [5]–[7]
As 4 K signal generation and processing matures, we expect that the generation of quantized pulse sequences without room temperature electronics will be realized

Summary

INTRODUCTION

Superconducting circuit quantum electrodynamics experiments form the basis for many quantum computing technologies [1]–[3]. JJ-based digital logic elements—generally referred to here as single flux quantum (SFQ) electronics—have been proposed and initial demonstrations have shown them to be a potential solution to scaling quantum computing technologies to larger numbers of qubits [5]–[7]. These logic elements, when operated at ∼10 mK in close proximity to qubits, create fast pulses with quantized voltage-time area that can be used for high-fidelity qubit state preparation. This will become an important experimental concern when scaling to larger numbers of SFQ-based or JAWS-based qubit control

JAWS DECRIPTION

QUBIT MEASUREMENT I

QUBIT MEASUREMENT II

CONCLUSION