Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1410.0552 · Physical Review Letters

Experimental Violation of Bell-like Inequalities By Electronic Shot Noise

Jean-Charles Forgues, Christian Lupien, Bertrand Reulet

Published Apr 2, 2015• 36 citations
arXivHTMLPDF

Abstract

We report measurements of the correlations between electromagnetic field quadratures at two frequencies f1=7 GHz and f1=7.5 GHz of the radiation emitted by a tunnel junction placed at very low temperature and excited at frequency f1+f2. We demonstrate the existence of two-mode squeezing and violation of a Bell-like inequality, thereby proving the existence of entanglement in the quantum shot noise radiated by the tunnel junction.

DOI
10.1103/physrevlett.114.130403

Related papers

Observation of Squeezing in the Electron Quantum Shot Noise of a Tunnel Junction

Gabriel Gasse, Christian Lupien, Bertrand Reulet

We report the measurement of the fluctuations of the two quadratures of the electromagnetic field generated by a quantum conductor, a dc- and ac-biased tunnel junction placed at very low temperature. We observe that the variance of the fluctuations on one quadrature can go below that of vacuum, i.e., that the radiated field is squeezed. This demonstrates the quantum nature of the radiated electromagnetic field.

arXiv:1306.3913•Physical Review Letters•Sep 25, 2013•41 citations

Non-classical radiation emission by a coherent conductor

Jean-Charles Forgues, Gabriel Gasse, Christian Lupien +1 more

We report experimental evidence that the microwave electromagnetic field generated by a normal conductor, here a tunnel junction placed at ultra-low temperature, can be non-classical. By measuring the quadratures of the electromagnetic field at one or two frequencies in the GHz range, we demonstrate the existence of squeezing as well as entanglement in such radiation. In one experiment, we observe that the variance of one quadrature of the photo-assisted noise generated by the junction goes below its vacuum level. In the second experiment, we demonstrate the existence of correlations between the quadratures taken at two frequencies, which can be stronger than allowed by classical mechanics, proving that the radiation at those two frequencies are entangled. 1

arXiv:1612.06337•Comptes Rendus Physique•Jul 18, 2016•9 citations

Emission of Microwave Photon Pairs by a Tunnel Junction

Jean-Charles Forgues, Christian Lupien, Bertrand Reulet

We report the observation of photon pairs in the photoassisted shot noise of a tunnel junction in the quantum regime at very high frequency and very low temperature. We have measured the fluctuations of the noise power generated by the junction at two different frequencies, f(1) = 4.4 and f(2) = 7.2 GHz, while driving the junction with a microwave excitation of frequency f(0) = f(1) + f(2). We observe clear correlations between the fluctuations of the two noise powers even when the mean photon number per measurement is much smaller than one. This is strong evidence for photons being emitted in pairs. We also demonstrate that the electromagnetic field generated by the junction exhibits two-mode amplitude squeezing, a proof of its nonclassicality. The data agree very well with predictions based on the fourth cumulant of the current fluctuations generated by the junction.

arXiv:1403.5578•Physical Review Letters•Jul 25, 2014•29 citations

Photon-pair shot noise in electron shot noise

Jean Olivier Simoneau, Stéphane Virally, Christian Lupien +1 more

We report the measurement of the statistics of photons in the nonclassical radiation emitted by a tunnel junction. This is obtained by measuring up to the fourth cumulant of the voltage fluctuations generated by the sample. When the electron shot noise generates a squeezed electromagnetic field, the measurement provides a strong signature of the presence of photon pairs, characterized by a Fano factor of the photon flux above unity.

arXiv:1605.02790•Physical review. B./Physical review. B•Feb 22, 2017•11 citations

Squeezing electronic noise with two tones

C. Paradis, Pierre Février, Edouard Pinsolle +1 more

We have calculated and measured the effect of two ac excitations on the quantum shot noise of a tunnel junction. Using a phase-sensitive detection, we demonstrate that the junction generates squeezed microwave, in agreement with theory. While being weak, this squeezing should be extremely broadband.

Applied Physics Letters•Jun 26, 2023•2 citations

Proposal for Production and Detection of Entangled Electron-Hole Pairs in a Degenerate Electron Gas

C. W. J. Beenakker, Clive Emary, M. Kindermann +1 more

We demonstrate theoretically that the shot noise produced by a tunnel barrier in a two-channel conductor violates a Bell inequality. The nonlocality is shown to originate from entangled electron-hole pairs created by tunneling events-without requiring electron-electron interactions. The degree of entanglement (concurrence) equals 2(T1T2)(1/2)(T1+T2)(-1), with T1,T2<<1 the transmission eigenvalues. A pair of edge channels in the quantum Hall effect is proposed as an experimental realization.

arXiv:cond-mat/0305110•Physical Review Letters•Oct 1, 2003•195 citations
We report measurements of the correlations between electromagnetic field quadratures at two frequencies f1=7 GHz and f1=7.5 GHz of the radiation emitted by a tunnel junction placed at very low temperature and excited at frequency f1+f2. We demonstrate the existence of two-mode squeezing and violation of a Bell-like inequality, thereby proving the existence of entanglement in the quantum shot noise radiated by the tunnel junction.
We report experimental evidence that the microwave electromagnetic field generated by a normal conductor, here a tunnel junction placed at ultra-low temperature, can be non-classical. By measuring the quadratures of the electromagnetic field at one or two frequencies in the GHz range, we demonstrate the existence of squeezing as well as entanglement in such radiation. In one experiment, we observe that the variance of one quadrature of the photo-assisted noise generated by the junction goes below its vacuum level. In the second experiment, we demonstrate the existence of correlations between the quadratures taken at two frequencies, which can be stronger than allowed by classical mechanics, proving that the radiation at those two frequencies are entangled. 1
We report the observation of photon pairs in the photoassisted shot noise of a tunnel junction in the quantum regime at very high frequency and very low temperature. We have measured the fluctuations of the noise power generated by the junction at two different frequencies, f(1) = 4.4 and f(2) = 7.2 GHz, while driving the junction with a microwave excitation of frequency f(0) = f(1) + f(2). We observe clear correlations between the fluctuations of the two noise powers even when the mean photon number per measurement is much smaller than one. This is strong evidence for photons being emitted in pairs. We also demonstrate that the electromagnetic field generated by the junction exhibits two-mode amplitude squeezing, a proof of its nonclassicality. The data agree very well with predictions based on the fourth cumulant of the current fluctuations generated by the junction.
We demonstrate theoretically that the shot noise produced by a tunnel barrier in a two-channel conductor violates a Bell inequality. The nonlocality is shown to originate from entangled electron-hole pairs created by tunneling events-without requiring electron-electron interactions. The degree of entanglement (concurrence) equals 2(T1T2)(1/2)(T1+T2)(-1), with T1,T2<<1 the transmission eigenvalues. A pair of edge channels in the quantum Hall effect is proposed as an experimental realization.