Protocol for certifying entanglement in surface spin systems using a scanning tunneling microscope
Rik Broekhoven (TU Delft - QN/Otte Lab, Kavli institute of nanoscience Delft)
Curie Lee (Ewha Womans University, Institute for Basic Science (IBS))
Soo Hyon Phark (Institute for Basic Science (IBS), Ewha Womans University)
Sander Otte (TU Delft - QN/Otte Lab, Kavli institute of nanoscience Delft)
Christoph Wolf (Ewha Womans University, Institute for Basic Science (IBS))
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Abstract
Certifying quantum entanglement is a critical step toward realizing quantum-coherent applications. In this work, we show that entanglement of spins can be unambiguously evidenced in a scanning tunneling microscope with electron spin resonance by exploiting the fact that entangled states undergo a free time evolution with a distinct characteristic time constant that clearly distinguishes it from the time evolution of non-entangled states. By implementing a phase control scheme, the phase of this time evolution can be mapped back onto the population of one entangled spin, which can then be read out reliably using a weakly coupled sensor spin in the junction of the scanning tunneling microscope. We demonstrate through open quantum system simulations with currently available spin coherence times of T2 ≈ 300 ns, that a signal directly correlated with the degree of entanglement can be measured at temperatures of 100–400 mK accessible in sub-Kelvin scanning tunneling microscopes.
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