Entanglement, loss, and quantumness: When balanced beam splitters are best
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#Entanglement
#PhaseEstimation
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Abstract: Entanglement generation by beam splitters lies at the heart of quantum optics. Yet, the conjecture that maximal entanglement for any state interfered with the vacuum is generated by beam splitters with equal reflection and transmission probabilities has remained unproven for almost two decades, despite overwhelming positive evidence [1]. I will report on our recent proof of this conjecture that led to monotonicity and convexity properties for quantum states undergoing photon loss [2]. Because of the interplay between information theoretic concepts such as entropy and physical considerations such as quantum system design, noise, and loss, our results have numerous ramifications in development of applications and advancing our understanding of quantum physics [3]. They extend to measures of similarity between states, yield to new inequalities for quasiprobability distributions and prove the conjecture in [4] that the quadrature coherence scale always stops certifying nonclassicality at 50% loss.
[1] Asboth et al. Phy. Rev. Lett. 94 (17), 173602 (2005)
[2] Lupu-Gladstein et al. Arxiv:2411.03423 (2024)
[3] Hertz et al. Arxiv:2501.02047 (2025)
[4] Hertz et al. Phys. Rev. A 110, 012408 (2024)
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Pavillon Principal B-304, Polytechnique Montréal
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Montréal, Quebec
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Canada
H3T 1J4
- Starts
21 August 2025 01:00 AM UTC
- Ends
08 September 2025 02:00 PM UTC
- No Admission Charge
Speakers
Anaelle Hertz of Research Associate - National Research Council Canada
Topic:
Entanglement, loss, and quantumness: When balanced beam splitters are best
Abstract: Entanglement generation by beam splitters lies at the heart of quantum optics. Yet, the conjecture that maximal entanglement for any state interfered with the vacuum is generated by beam splitters with equal reflection and transmission probabilities has remained unproven for almost two decades, despite overwhelming positive evidence [1]. I will report on our recent proof of this conjecture that led to monotonicity and convexity properties for quantum states undergoing photon loss [2]. Because of the interplay between information theoretic concepts such as entropy and physical considerations such as quantum system design, noise, and loss, our results have numerous ramifications in development of applications and advancing our understanding of quantum physics [3]. They extend to measures of similarity between states, yield to new inequalities for quasiprobability distributions and prove the conjecture in [4] that the quadrature coherence scale always stops certifying nonclassicality at 50% loss.
[1] Asboth et al. Phy. Rev. Lett. 94 (17), 173602 (2005)
[2] Lupu-Gladstein et al. Arxiv:2411.03423 (2024)
[3] Hertz et al. Arxiv:2501.02047 (2025)
[4] Hertz et al. Phys. Rev. A 110, 012408 (2024)
Biography:
Short Bio: Anaelle Hertz is a research associate at the National Research Council of Canada (QN), specializing in quantum information and quantum optics. After studies in Physics at l’Université de Montréal, a PhD at l’Université Libre de Bruxelles (Belgium) and two postdoctoral fellowships at the Centre national de la recherche scientifique (CNRS) (France) and at the University of Toronto, Anaelle joined NRC. Anaelle parenting journey has aligned with her research career. As a mother of three young children, Anaelle also advocates for parents and caregivers in STEM through her leadership role in the international organization Mothers in Science.
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