Entanglement in a fermionic two-particle interferometer

Bei Zeng

Vittorio Giovannetti

Hong-Ou-Mandel interferometry allows one to detect the presence of entanglement in two-photon input states. The same result holds for two-particle input states which obey fermionic statistics. In the latter case, however, antibouncing introduces qualitative differences in the interferometer response. This effect is analyzed in a gedanken experiment where the particles entering the interferometer are assumed to belong to a one-parameter family of quons which continuously interpolate between the bosonic and fermionic statistics.

Gilles Brassard A, Tal Mor

Peter Samuelsson, Izhar Neder, Μ. Büttiker

In this work we discuss a theory for entanglement generation, characterization and detection in fermionic two-particle interferometers (2PIs) at finite temperature. The motivation for our work is provided by the recent experiment by the Heiblum group (Neder et al 2007 Nature 448 333) realizing the two particle interferometer proposed by Samuelsson et al (2004 Phys. Rev. Lett. 92 026805). The experiment displayed a clear two-particle Aharonov–Bohm effect, however with an amplitude suppressed due to finite temperature and dephasing. This raised qualitative as well quantitative questions about entanglement production and detection in mesoscopic conductors at finite temperature. As a response to these questions, in our recent work (Samuelsson et al 2009 Phys. Rev. Lett. 102 106804), we presented a general theory for finite temperature entanglement in mesoscopic conductors. Applied to the 2PI we showed that the emitted two-particle state in the experiment was clearly entangled. Moreover, we demonstrated that the entanglement of the reduced two-particle state, reconstructed from measurements of average currents and current cross correlations, constitutes a lower bound to the entanglement of the emitted state. The present work provides an extended and more detailed discussion of these findings.

Peter Alexander Bouvrie, A. P. Majtey, Francisco Figueiredo +1 more

Abstract Feshbach molecules forming a Bose–Einstein condensate (BEC) behave as non-ideal bosonic particles due to their underlying fermionic structure. We study the observable consequences of the fermion exchange interactions in the interference of molecular BECs for entangled-enhanced precision measurements. Our many-body treatment of the molecular condensate is based on an ansatz of composite two-fermion bosons which accounts for all possible fermion exchange correlations present in the system. The Pauli principle acts prohibitively on the particle fluctuations during the interference process leading to a loss of precision in phase estimations. However, we find that, in the regime where molecular dissociations do not jeopardize the interference dynamics, measurements of the phase can still be performed with a precision beyond the classical limit comparable to atomic interferometers. We also show that the effects of Pauli principle increases with the noise of the particle detectors such that molecular interferometers would require more efficient detectors.

Yanhua H. Shih