Readout methods and devices for Josephson-junction-based solid-state qubits

TL;DR

This paper reviews and develops dispersive low-dissipation readout techniques for Josephson-junction qubits, including a formalism for charge qubit measurement via quantum capacitance and formulas for readout time.

Contribution

It introduces a formalism for charge qubit readout using quantum capacitance and provides explicit formulas for readout time, advancing measurement methods for Josephson-junction qubits.

Findings

Dispersive low-dissipation readout techniques enable single-shot qubit state detection.

A formalism for measuring effective quantum capacitance of charge qubits is developed.

Explicit formulas for readout time are derived.

Abstract

We discuss the current situation concerning measurement and readout of Josephson-junction based qubits. In particular we focus attention of dispersive low-dissipation techniques involving reflection of radiation from an oscillator circuit coupled to a qubit, allowing single-shot determination of the state of the qubit. In particular we develop a formalism describing a charge qubit read out by measuring its effective (quantum) capacitance. To exemplify, we also give explicit formulas for the readout time.