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Q: Fachverband Quantenoptik und Photonik

Q 45: Mechanical, Macroscopic, and Continuous-variable Quantum Systems (joint session QI/Q)

Q 45.4: Vortrag

Mittwoch, 12. März 2025, 15:30–15:45, HS IX

Learning quantum states of continuous-variable systems — Francesco Mele¹, Antonio Mele², •Lennart Bittel², Jens Eisert², Vittorio Giovannetti¹, Ludovico Lami³, Lorenzo Leone², and Salvatore Oliviero¹ — ¹NEST, Scuola Normale Superiore and Istituto Nanoscienze, Piazza dei Cavalieri 7, IT-56126 Pisa, Italy — ²Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195 Berlin, Germany — ³Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands

Quantum state tomography, aimed at deriving a classical description of an unknown state from measurement data, is a fundamental task in quantum physics. In this work, we analyse the ultimate achievable performance of tomography of continuous-variable systems, such as bosonic and quantum optical systems. We prove that tomography of these systems is extremely inefficient in terms of time resources. On a more positive note, we prove that tomography of Gaussian states is efficient. To accomplish this, we answer a fundamental question for the field of continuous-variable quantum information: if we know with a certain error the first and second moments of an unknown Gaussian state, what is the resulting trace-distance error that we make on the state? Lastly, we demonstrate that tomography of non-Gaussian states prepared through Gaussian unitaries and a few local non-Gaussian evolutions is efficient and experimentally feasible.

Keywords: Tomography; Learning quantum states; Bosonic systems; Gaussian states