Quantum Thermodynamics of Many-Body Driven Systems

Project Information

QuoMoDys

Grant agreement ID: 101031549

DOI

10.3030/101031549

Project terminated on 9 January 2024

EC signature date 3 March 2021

Start date 1 June 2022

End date 28 March 2025

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 196 707,84

EU contribution

€ 196 707,84

Coordinated by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 1 - QuoMoDys (Quantum Thermodynamics of Many-Body Driven Systems)

Reporting period: 2022-06-01 to 2024-05-31

Summary of the context and overall objectives of the project

The project has addressed the problem of probing and characterizing quantum entanglement in quantum many-body systems, especially in the presence of drive and dissipation. A special focus has been placed on the study of exciton-polariton systems, which represent a very relevant experimental platform to investigate such fundamental questions.

In particular, we have :
- developed new methods of fundamental interest to quantum information science to detect quantum entanglement in many-body systems
- studied, in a joint theory-experiment collaboration, the prospects of exciton-polariton platforms to generated quantum-entangled photon pairs.

Quantum entanglement in many-body systems represent a key physical property in the context of quantum technologies, especially for quantum computing and sensing. Many fundamental questions remain to be addressed before quantum computing hardwares can find a route towards technology applications. The QuoMoDys project contributes to asking and answering such fundamental questions.

The main conclusions of the action are that:
- on the quantum information theory level, certification of relevant properties of quantum many-body systems is possible, even in the absence of full-state tomography. This is a key asset for quantum technologies given that full-state tomography is unfeasible beyond about a dozen of qubits.
- on the more specific platform of exciton-polaritons, the interplay of intrinsic quantum noise with the thermal noise of the solid-state lattice in which the system is embedded had been overlooked in previous works; our work lays the ground to future developments devoted to enhance the quantum contribution, given potentially rise to quantum entanglement among the photons leaving the system.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The main results of the project are, more specifically :
- the development of a new algorithm to infer entanglement criteria tailored to large-spin atomic ensembles, going beyond spin-squeezing inequalities (https://arxiv.org/abs/2203.13547)
- the publication of a review on methods to probe quantum entanglement in many-body systems (https://arxiv.org/abs/2302.00640)
- the publication of a joint theory-experiment work on exciton-polariton systems, which clarifies the interplay of quantum and thermal noise in such systems (https://arxiv.org/abs/2304.08677)
- the development of a new algorithm to certify the resource content of a quantum system for quantum metrology applications (https://arxiv.org/abs/2306.12711)
- a fundamental breakthrough for the certification of quantum hardwares, at the intersection of quantum information science and condensed matter theory (https://arxiv.org/abs/2310.05844)

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

All the above-mentioned achievements go beyond the state of the art.
- We provide new ways to circumvent the "curse of dimensionality" for the certfication of quantum hardwares, namely the impossibility to fully characterize them because of the exponential growth of the Hilbert space dimension with the system size. We circumvent this issue by providing efficient ways to certify relevant properties of the system in view of their use in the context of quantum-technology application, without requiring quantum-state tomography. We achieve this by leveraging on fundamental breakthrough in quantum information science over the past decade, namely the use of so-called semidefinite programming approaches, which are special class of convex optimization methods developed by mathematicians, and more recently applied in quantum information theory.
- In the context of exciton-polariton systems, we clarify for the first time the key role played by thermal phonons of the solid-state crystal in which the system is embedded. This aspect had been overlooked in previous works, and our contribution is fundamental in that it clearly shows the parameter regime in which one can expect quantum entanglement to emerge in the system, which is a key step in view of future quantum technology applications.

Sketch of the two mechanisms creating Bogoliubov excitations in a quantum fluid of light