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oe1(光电查) - 科学论文

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  • Measurement-device-independent and arbitrarily loss-tolerant verification of quantum steering

    摘要： We propose a method to verify quantum steering for two-qubit states with an arbitrary amount of null results when both the steering and steered parties cannot be trusted. We converted the steering inequality proposed in a recent article [Phys. Rev. X 2, 031003 (2012)] to a corresponding measurement-device-independent steering criterion that depends on the heralding efficiency of the steering party, number of measurement settings, and imperfection of the state preparation. As a result, for a relative frequency of valid measurement outcomes ηH, the steering can be verified using a number of different measurement settings larger than 1/ηH and maximally entangled states. Furthermore, steerability is guaranteed as long as the measurement efficiency of the steered party is nonzero. Our result is useful for loss-tolerant and measurement-device-independent steering tasks.

    关键词： two-qubit states,loss-tolerant,quantum steering,measurement-device-independent,heralding efficiency

    更新于2025-09-23 15:22:29

  • Universal detection of entanglement in two-qubit states using only two copies

    摘要： We revisit the problem of detection of entanglement of an unknown two-qubit state using minimal resources. Using weak values and just two copies of an arbitrary two-qubit state, we present a protocol where a postselection measurement in the computational basis provides enough information to identify if the state is entangled or not. Our protocol enables complete state identification with a single-setting postselection measurement on two copies of the state. It follows that by restricting to pure states, the global interaction required for determining the weak values can be realized by local operations. We further show that our protocol is robust against errors arising from inappropriate global interactions applied during weak value determination.

    关键词： weak values,quantum information,two-qubit states,entanglement detection

    更新于2025-09-23 15:22:29