Generating spin-entangled electron pairs in normal conductors using voltage pulses

Lebedev, A. V.; Lesovik, G. B.; Blatter, G.

doi:10.1103/physrevb.72.245314

Cited by 37 publications

(17 citation statements)

References 35 publications

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“…Antibunching of the electrons and holes with the levitons at the beam splitter changes the leviton partition statistics, and the noise variations provide the energy density matrix elements of the levitons. This demonstration of quantum tomography makes the developing field of electron quantum optics with ballistic conductors a new test-bed for quantum information with fermions 20,[22][23][24] . These results may find direct application in probing the entanglement of electron flying quantum bits 25 , electron decoherence 17 and electron interactions.…”

mentioning

confidence: 96%

“…Here we show that such measurements are possible despite the extreme noise sensitivity required, and present the reconstructed wavefunction quasiprobability, or Wigner distribution function 17 , of single electrons injected into a ballistic conductor. Many identical electrons are prepared in well-controlled quantum states called levitons 18 by repeatedly applying Lorentzian voltage pulses to a contact on the conductor [19][20][21] . After passing through an electron beam splitter, the levitons are mixed with a weak-amplitude fermionic field formed by a coherent superposition of electron-hole pairs generated by a small alternating current with a frequency that is a multiple of the voltage pulse frequency 16 .…”

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confidence: 99%

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Quantum tomography of an electron

Jullien

Roulleau

Roche

et al. 2014

Nature

189

272

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The complete knowledge of a quantum state allows the prediction of the probability of all possible measurement outcomes, a crucial step in quantum mechanics. It can be provided by tomographic methods which have been applied to atomic, molecular, spin and photonic states. For optical or microwave photons, standard tomography is obtained by mixing the unknown state with a large-amplitude coherent photon field. However, for fermions such as electrons in condensed matter, this approach is not applicable because fermionic fields are limited to small amplitudes (at most one particle per state), and so far no determination of an electron wavefunction has been made. Recent proposals involving quantum conductors suggest that the wavefunction can be obtained by measuring the time-dependent current of electronic wave interferometers or the current noise of electronic Hanbury-Brown/Twiss interferometers. Here we show that such measurements are possible despite the extreme noise sensitivity required, and present the reconstructed wavefunction quasi-probability, or Wigner distribution function, of single electrons injected into a ballistic conductor. Many identical electrons are prepared in well-controlled quantum states called levitons by repeatedly applying Lorentzian voltage pulses to a contact on the conductor. After passing through an electron beam splitter, the levitons are mixed with a weak-amplitude fermionic field formed by a coherent superposition of electron-hole pairs generated by a small alternating current with a frequency that is a multiple of the voltage pulse frequency. Antibunching of the electrons and holes with the levitons at the beam splitter changes the leviton partition statistics, and the noise variations provide the energy density matrix elements of the levitons. This demonstration of quantum tomography makes the developing field of electron quantum optics with ballistic conductors a new test-bed for quantum information with fermions. These results may find direct application in probing the entanglement of electron flying quantum bits, electron decoherence and electron interactions. They could also be applied to cold fermionic (or spin-1/2) atoms.

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mentioning

confidence: 96%

mentioning

confidence: 99%

Quantum tomography of an electron

Jullien

Roulleau

Roche

et al. 2014

Nature

189

272

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“…In contrast, very little is known about the continuum, that is, the dynamics of degrees of freedom, which are allowed to propagate inside a system. A few works propose setups for 'flying qubits' [1][2][3][4][5][6] that encode the quantum information into the paths taken by the electrons. Those systems could be realized in Mach-Zehnder interferometers in the quantum Hall regime [7][8][9] or Aharonov-Bohm geometries 10 .…”

mentioning

confidence: 99%

Dynamical control of interference using voltage pulses in the quantum regime

Gaury¹,

Waintal²

2014

Nat Commun

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As a general trend, nanoelectronics experiments are shifting towards frequencies so high that they become comparable to the device's internal characteristic time scales, resulting in new opportunities for studying the dynamical aspects of quantum mechanics. Here we theoretically study how a voltage pulse (in the quantum regime) propagates through an electronic interferometer (Fabry-Perot or Mach-Zehnder). We show that extremely fast pulses provide a conceptually new tool for manipulating quantum information: the possibility to dynamically engineer the interference pattern of a quantum system. Striking physical signatures are associated with this new regime: restoration of the interference in presence of large bias voltages; negative currents with respect to the direction of propagation of the voltage pulse; and oscillation of the total transmitted charge with the total number of injected electrons. The present findings have been made possible by the recent unlocking of our capability for simulating time-resolved quantum nanoelectronics of large systems.

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“…For the single-electron sources, we consider the application of Lorentzian-shaped voltage pulses to the contacts [7,8,[55][56][57][58]. A driven mesoscopic capacitor [5] can be used instead.…”

Section: Observing Single-electron Entanglementmentioning

confidence: 99%

Single-electron entanglement and nonlocality

et al. 2016

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Motivated by recent progress in electron quantum optics, we revisit the question of single-electron entanglement, specifically whether the state of a single electron in a superposition of two separate spatial modes should be considered entangled. We first discuss a gedanken experiment with singleelectron sources and detectors, and demonstrate deterministic (i. e. without post-selection) Bell inequality violation. This implies that the single-electron state is indeed entangled and, furthermore, nonlocal. We then present an experimental scheme where single-electron entanglement can be observed via measurements of the average currents and zero-frequency current cross-correlators in an electronic Hanbury Brown-Twiss interferometer driven by Lorentzian voltage pulses. We show that single-electron entanglement is detectable under realistic operating conditions. Our work settles the question of single-electron entanglement and opens promising perspectives for future experiments.

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Generating spin-entangled electron pairs in normal conductors using voltage pulses

Cited by 37 publications

References 35 publications

Quantum tomography of an electron

Quantum tomography of an electron

Dynamical control of interference using voltage pulses in the quantum regime

Single-electron entanglement and nonlocality

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