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Quantum Entanglement in Nanoelectronic Devices by Noise Measurements
Third-party funded project
Project title Quantum Entanglement in Nanoelectronic Devices by Noise Measurements
Principal Investigator(s) Schönenberger, Christian
Organisation / Research unit Departement Physik / Experimentalphysik Nanoelektronik (Schönenberger)
Project start 01.01.2014
Probable end 31.12.2014
Status Completed
Abstract

One of the present day challenges in quantum electronics is to create entangled electron pairs with high efficiency and distribute the entanglement over long distances with high fidelity. Whereas schemes for the local generation of entangled electron pairs have been demonstrated, for example using Cooper-pairs or double quantum dots, the distribution remains a challenge. As compared to photons the distribution of electrons in the solid-state is much harder, because unlike photons electrons in devices are strongly interacting and part of a many-body system, the Fermi sea. The spin of an electron is considered an ideal quantum degree of freedom because large spin-coherence times have been demonstrated in highmobility materials and recently also in graphene. Hence, the entanglement of a two electron state, prepared for example in the maximally entangled spin singlet state, may therefore persist over distances much larger than a micrometer. Until today, however, no transport experiment could demonstrate entanglement via a counts at two distant detectors are analyzed, theorists have proposed to use noise correlation experiments to mimic coincidence counts and to construct a Bell inequality. In a certain parameter range, a Bell-test based on shot-noise correlation is indeed possible. However, noise may be suppressed due to many-body screening effects. Due to the requirement to measure noise with a resolution of mK (milli-Kelvin) in devices with high impedances, typically larger than 100 kOhm frequencies in the 100 MHz to 10 GHz window to overcome spurious low frequency 1/f noise caused by the trapping and detrapping of charge in oxide layers. Cryogenic amplifiers have noise temperatures of a few Kelvins. One therefore has to average over a very long time to achieved the required accuracy. Here, we propose to build an unique cryogenic systems for noise-correlation experiments implementing parametric amplifiers which can operate at the quantum limit and dedicated impedance matching circuits. This will provide enough resolution to make possible the measurement of entanglement by non-local noise correlation experiments not only using second-order moments, but even higher ones.

 

 

Financed by Swiss National Science Foundation (SNSF)
   

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09/05/2024