Abstract
Devices to generate on-demand non-local spin entangled electron pairs have potential application as solid-state analogues of the entangled photon sources used in quantum optics. Recently, Andreev entanglers that use two quantum dots as filters to adiabatically split and separate the quasi-particles of Cooper pairs have shown efficient splitting through measurements of the transport charge but the spin entanglement has not been directly confirmed. Here we report measurements on parallel quantum dot Josephson junction devices allowing a Josephson current to flow due to the adiabatic splitting and recombination of the Cooper pair between the dots. The evidence for this non-local transport is confirmed through study of the non-dissipative supercurrent while tuning independently the dots with local electrical gates. As the Josephson current arises only from processes that maintain the coherence, we can confirm that a current flows from the spatially separated entangled pair.
Highlights
Devices to generate on-demand non-local spin entangled electron pairs have potential application as solid-state analogues of the entangled photon sources used in quantum optics
The nondissipative Josephson current that flows in the presented system is captured in the Josephson energy of the junction (EJ), which indicates the potential energy stored and is proportional to the critical current (EJpIc)
When one quantum dots (QDs) is tuned to be OFF resonance, the Josephson current arising from local Cooper pair tunnelling through that QD is negligible as a result of the large U
Summary
Devices to generate on-demand non-local spin entangled electron pairs have potential application as solid-state analogues of the entangled photon sources used in quantum optics. We report measurements on parallel quantum dot Josephson junction devices allowing a Josephson current to flow due to the adiabatic splitting and recombination of the Cooper pair between the dots. The evidence for this non-local transport is confirmed through study of the non-dissipative supercurrent while tuning independently the dots with local electrical gates. Measurements have probed the Cooper pair splitting through observation of non-local charge signals[14,15,16] and correlation of the current fluctuations[17] In these first measurements, the entangled spin state is not directly confirmed. By measuring the supercurrent in this device, we detect its enhancement when Cooper pairs from one lead are split between the two QDs and recombined in the second lead
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