Interference between two indistinguishable electrons from independent sources

Neder, Izhar; Ofek, Nissim; Chung, Yunchul; Heiblum, Moty; Mahalu, D.; Umansky, V.

doi:10.1038/nature05955

Cited by 297 publications

(411 citation statements)

References 22 publications

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“…Although the measured average intensity distribution is uniform, transverse Anderson localization nevertheless underlies the observed anti-correlation. [5][6][7], atoms in cold Fermi gases [8,9], as well as interacting photons in nonlinear media [10]. In typical optical HBT scenarios, such as the original determination of the angular size of the star Sirius A [2], the radiation source is random while the medium transmitting the incoherent wave is deterministic.…”

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confidence: 99%

“…The Hanbury-Brown and Twiss (HBT) interferometer [2,3] can reveal this acquired coherence by correlating intensity fluctuations at two different points. The HBT effect is a universal wave phenomenon that has been observed with free electrons [4], electrons in solid-state devices [5][6][7], atoms in cold Fermi gases [8,9], as well as interacting photons in nonlinear media [10]. In typical optical HBT scenarios, such as the original determination of the angular size of the star Sirius A [2], the radiation source is random while the medium transmitting the incoherent wave is deterministic.…”

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confidence: 99%

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Hanbury Brown and Twiss anticorrelation in disordered photonic lattices

et al. 2016

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We report measurements of Hanbury-Brown and Twiss correlation of coherent light transmitted through disordered one-dimensional photonic lattices. Although such a lattice exhibits transverse Anderson localization when a single input site is excited, uniform excitation precludes its observation. By examining the Hanbury-Brown Twiss correlation for a uniformly excited disordered lattice, we observe intensity anti-correlations associated with photon anti-bunching -a signature of nonGaussian statistics. Although the measured average intensity distribution is uniform, transverse Anderson localization nevertheless underlies the observed anti-correlation. [5][6][7], atoms in cold Fermi gases [8,9], as well as interacting photons in nonlinear media [10]. In typical optical HBT scenarios, such as the original determination of the angular size of the star Sirius A [2], the radiation source is random while the medium transmitting the incoherent wave is deterministic. One might consider an alternative scenario in which a deterministic coherent input probes a scattering medium, which becomes itself the source of randomness. HBT measurements carried out on the emerging partially coherent light can provide insights into the nature of the disorder in the medium.A particularly useful system for testing the impact of disorder on optical statistics is that of evanescently coupled waveguide arrays (or photonic lattices) with randomness introduced in the transverse direction [11]. This setting emulates time evolution of quantum-mechanical waves in time-independent disordered potentials. Indeed, by coupling a coherent input to a single lattice site, Anderson localization [12] has been observed in the transverse direction upon ensemble averaging [13][14][15][16]. Beyond the mean intensity observed in such experiments, unique features of the higher-order field correlations involved in the HBT effect have only recently been explored [17][18][19][20][21][22][23]. Indeed, HBT measurements can distinguish between the so-called 'diagonal' and 'off-diagonal' classes of lattice disorder, whereas such a delineation is not possible by observing the mean field alone [18]. Furthermore, path-entangled photon pairs propagating along such lattices can emulate the quantummechanical waves associated with fermions and bosons [17], and can exhibit co-localization and anti-localization when the illumination is extended [19,21].In this letter, we report measurements of HBT interference in disordered photonic lattices excited uniformly with an extended coherent optical field. Light emerging from such a system is no longer coherent after ensemble averaging. The intensity fluctuations at any site indicate a thermalization of optical statistics [24,25]. Here we measure the correlations between fluctuations at pairs of lattice sites. It is revealed -surprisingly -that at certain separations anti-correlations emerge. This result implies that the optical field exiting the lattice is characterized by non-Gaussian statistics that correspond to photon antibunching....

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Hanbury Brown and Twiss anticorrelation in disordered photonic lattices

et al. 2016

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“…Among its various applications, quantum interference has been used successfully as a tool to investigate properties of particles such as monitoring correlation and entanglement as demonstrated in MachZehnder interferometery [7,8], Aharonov-Bohm interferometery [9,10], Hanbury Brown-Twiss interferometery [11,12], and the electronic analogue of the Hong-OuMandel device [13,14]. Among all the striking phenomena, it is particularly interesting to note that quantum interference is extremely suitable for studying coupling between different quantum systems [15][16][17], which is crucial for the design of integrated quantum circuits.…”

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confidence: 99%

Interference Effects in a Tunable Quantum Point Contact Integrated with an Electronic Cavity

et al. 2017

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We show experimentally how quantum interference can be produced using an integrated quantum system comprising an arch-shaped short quantum wire (or quantum point contact, QPC) of 1D electrons and a reflector forming an electronic cavity. On tuning the coupling between the QPC and the electronic cavity, fine oscillations are observed when the arch QPC is operated in the quasi-1D regime. These oscillations correspond to interference between the 1D states and a state which is similar to the Fabry-Perot state and suppressed by a small transverse magnetic field of AE60 mT. Tuning the reflector, we find a peak in resistance which follows the behavior expected for a Fano resonance. We suggest that this is an interesting example of a Fano resonance in an open system which corresponds to interference at or near the Ohmic contacts due to a directly propagating, reflected discrete path and the continuum states of the cavity corresponding to multiple scattering. Remarkably, the Fano factor shows an oscillatory behavior taking peaks for each fine oscillation, thus, confirming coupling between the discrete and continuum states. The results indicate that such a simple quantum device can be used as building blocks to create more complex integrated quantum circuits for possible applications ranging from quantum-information processing to realizing the fundamentals of complex quantum systems.

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“…Based on the theoretical proposal [3] for a fermionic two-particle interferometer (2PI), see Fig. 1, Neder et al [4] were able to demonstrate interference between two electrons emitted from independent sources. In perfect agreement with theory, the interference pattern was visible in the current correlations but not in the average current.…”

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confidence: 99%

“…, and a Bell inequality is violated, Ω max Bp > 2 (Ω max Br > 2). The red ring denotes the parameters of the experiment [4], showing that while the emitted state is clearly entangled, Cp > 0, it is barely detectable by current and current correlation measurements, Cr ≈ 0.We are interested in finite temperature orbital [6] entanglement in a general mesoscopic system, shown in Fig. 3.…”

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Reduced and Projected Two-Particle Entanglement at Finite Temperatures

2009

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We present a theory for two-particle entanglement production and detection in mesoscopic conductors at finite temperature. The entanglement of the density matrix projected out of the emitted many-body state differs from the entanglement of the reduced density matrix, detectable by current correlation measurements. Under general conditions reduced entanglement constitutes a witness for projected entanglement. Applied to the recent experiment [Neder et al, Nature 448 333 (2007)] on a fermionic Hanbury Brown Twiss two-particle interferometer we find that despite an appreciable entanglement production in the experiment, the detectable entanglement is close to zero. 72.70.+m, 74.40.+k The last decade has witnessed an increasing interest in generation and detection of entanglement in mesoscopic conductors [1,2]. Entanglement is an ubiquitous quantum effect, it describes correlations between particles that can not be accounted for classically. A better understanding of entanglement of elementary charge carriers, or quasiparticles, is therefore of fundamental interest. Due to controllable system properties and coherent transport conditions, mesoscopic conductors constitute ideal systems for the investigation of quasiparticle entanglement. In a longer time perspective, the prospect of quantum information processing using spin or orbital quantum states of individual quasiparticles provides additional motivation for such an investigation.To date quasiparticle entanglement has remained experimentally elusive. However, recently an important step was taken towards a demonstration of entanglement in mesoscopic conductors. Based on the theoretical proposal [3] for a fermionic two-particle interferometer (2PI), see Fig. 1, Neder et al [4] were able to demonstrate interference between two electrons emitted from independent sources. In perfect agreement with theory, the interference pattern was visible in the current correlations but not in the average current. Under conditions of zero dephasing and temperature, the part of the emitted state with one electron in each detection region A,B would bewhere 1, 2 denote the sources. The wavefunction |Ψ s is maximally entangled, it is a singlet in orbital, or pseudo spin, space. However, in the experiment [4] a reduced amplitude (∼ 25%) of the current correlation oscillations was observed, suggesting an important effect of both dephasing and finite temperature. This raises two interesting and interrelated questions: are the electrons reaching the detectors at A and B entangled and if so, can this two-particle entanglement be unambiguously detected by measurements of currents and current correlators? In this work we provide an affirmative answer to both these questions. We present a general theory for twoparticle entanglement generation and detection in mesoscopic conductors at finite temperatures and apply it to the 2PI. Under very general conditions a nonzero entanglement of the reduced orbital density matrix, accessible by current and current correlation measurements [5], is shown ...

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Interference between two indistinguishable electrons from independent sources

Cited by 297 publications

References 22 publications

Hanbury Brown and Twiss anticorrelation in disordered photonic lattices

Hanbury Brown and Twiss anticorrelation in disordered photonic lattices

Interference Effects in a Tunable Quantum Point Contact Integrated with an Electronic Cavity

Reduced and Projected Two-Particle Entanglement at Finite Temperatures

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