Amplification and squeezing of quantum noise with a tunable Josephson metamaterial

TL;DR

This paper introduces a tunable Josephson metamaterial device that acts as a subquantum-limited microwave amplifier, capable of amplifying and squeezing quantum noise, which is crucial for quantum measurements and information processing.

Contribution

It presents a novel, tunable Josephson metamaterial device that achieves subquantum-limited amplification and 10 dB squeezing of quantum noise in the microwave frequency range.

Findings

Achieves 10 dB squeezing of quantum fluctuations.

Operates between 4 and 8 GHz with tunability.

Provides a low-noise amplification suitable for quantum measurements.

Abstract

It has recently become possible to encode the quantum state of superconducting qubits and the position of nanomechanical oscillators into the states of microwave fields. However, to make an ideal measurement of the state of a qubit, or to detect the position of a mechanical oscillator with quantum-limited sensitivity requires an amplifier that adds no noise. If an amplifier adds less than half a quantum of noise, it can also squeeze the quantum noise of the electromagnetic vacuum. Highly squeezed states of the vacuum serve as an important quantum information resource. They can be used to generate entanglement or to realize back-action-evading measurements of position. Here we introduce a general purpose parametric device, which operates in a frequency band between 4 and 8 GHz. It is a subquantum-limited microwave amplifier, it amplifies quantum noise above the added noise of commercial amplifiers, and it squeezes quantum fluctuations by 10 dB.