https://doi.org/10.1140/epjs/s11734-023-00989-0
Regular Article
Integrated conversion and photodetection of virtual photons in an ultrastrongly coupled superconducting quantum circuit
1
CNR-IMM, UoS Università, 95123, Catania, Italy
2
Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, Via S. Sofia 64, 95123, Catania, Italy
3
INFN Sez. Catania, 95123, Catania, Italy
4
Department of Experimental Physics, Comenius University, 84248, Bratislava, Slovakia
5
QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 15100, 00076, Aalto, Finland
a
luigi.giannelli@dfa.unict.it
Received:
6
June
2023
Accepted:
22
August
2023
Published online:
8
September
2023
The ground state of an artificial atom ultrastrongly coupled to quantized modes is entangled and contains an arbitrary number of virtual photons. The problem of their detection has been raised since the very birth of the field, but despite the theoretical efforts still awaits experimental demonstration. Recently, experimental problems have been addressed in detail showing that they can be overcome by combining an unconventional design of the artificial atom with advanced coherent control. In this work, we study a simple scheme of control-integrated continuous measurement, which makes remarkably favorable the tradeoff between measurement efficiency and backaction showing that the unambiguous detection of virtual photons can be achieved within state-of-the-art quantum technologies.
© The Author(s) 2023
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