On-chip microwave coherent source with in-situ control of the photon number distribution

TL;DR

This paper proposes a tunable on-chip microwave photon source using a superconducting circuit with a controllable coupler, enabling dynamic control of photon emission for quantum applications.

Contribution

It introduces a novel design for a tunable, on-chip microwave photon source with in-situ control of photon number distribution, avoiding direct manipulation of the source dynamics.

Findings

Demonstrates control of photon emission via external flux

Validates dynamical control of generated quantum states

Discusses potential for multi-reservoir implementations

Abstract

Coherent photon sources are key elements in different applications, ranging from quantum sensing to quantum computing. The possibility of designing and engineering superconducting circuits behaving like artificial atoms supports the realization of quantum optics protocols, including microwave photons generation. Here we propose and theoretically investigate a design that allows a tunable photon injection directly on-chip. Our approach enables control of the emission via an external knob while preserving, in principle, the stability and linewidth characteristics. This is achieved by replacing the conventional capacitive link between the source and the reservoir with a tunable coupler, with the advantage of avoiding direct dynamical manipulation of the photon source dynamics, providing pulsed control of the emission. We validate the dynamical control of the generated state under the effect of an external flux threading the tunable coupler and discuss the possibility of employing this scheme also in the context of multiple bosonic reservoirs.