Projective measurements are sufficient for recycling nonlocality

Abstract

Unsharp measurements are widely seen as the key resource for recycling the nonlocality of an entangled state shared between several sequential observers. Contrasting this, we here show that nonlocality can be recycled using only standard projective measurements, without using quantum ancillas. Focusing on the CHSH inequality, we determine the optimal trade-off in the Bell parameters for a maximally entangled two-qubit state in the presence of shared classical randomness. We then find that non-maximally entangled states make possible larger sequential violations, which contrasts the standard CHSH scenario. Furthermore, we show that nonlocality can be recycled even when only using projective measurements and local randomness. We discuss the implications of our results for experimental implementations of sequential nonlocality.

arXiv commentUpdated version. Typo corrected

References in corpus (25)

• Multiple Observers Can Share the Nonlocality of Half of an Entangled Pair by Using Optimal Weak Measurements
• Unbounded randomness certification using sequences of measurements
• Arbitrarily many independent observers can share the nonlocality of a single maximally entangled qubit pair
• Self-testing non-projective quantum measurements in prepare-and-measure experiments
• Sequential random access codes and self-testing of quantum measurement instruments
• Steering a single system sequentially by multiple observers
• Witnessing entanglement sequentially: Maximally entangled states are not special
• Three-observer Bell inequality violation on a two-qubit entangled state
• Experimental characterisation of unsharp qubit observables and sequential measurement incompatibility via quantum random access codes
• Semi-device-independent self-testing of unsharp measurements
• Facets of bipartite nonlocality sharing by multiple observers via sequential measurements
• Sharing non-locality and non-trivial preparation contextuality using same family of Bell expressions
• Sharing quantum nonlocality and genuine nonlocality with independent observables
• Device-Independent Certification of a Nonprojective Qubit Measurement
• Limitations on sharing Bell nonlocality between sequential pairs of observers
• Experimental Certification of Sustained Entanglement and Nonlocality after Sequential Measurements
• Observation of nonlocality sharing via not-so-weak measurements
• Sharing of tripartite nonlocality by multiple observers measuring sequentially at one side
• Quantum predictions for an unmeasured system cannot be simulated with a finite-memory classical system
• Experimental Demonstration of Sequential Quantum Random Access Codes
• Experimental Test of Sequential Weak Measurements for Certified Quantum Randomness Extraction
• Experimental certification of an informationally complete quantum measurement in a device-independent protocol
• Bounding sets of sequential quantum correlations and device-independent randomness certification
• Noise-robust preparation contextuality shared between any number of observers via unsharp measurements
• Recycling qubits for the generation of Bell nonlocality between independent sequential observers

Cited by in corpus (10)

• Quantum Correlation Sharing: A Review On Recent Progress From Nonlocality To Other Non-Classical Correlations
• Unbounded Sharing of Nonlocality Using Projective Measurements
• Quantifying the intrinsic randomness in sequential measurements
• Self-testing of multiple unsharpness parameters through sequential violations of non-contextual inequality
• Secure and robust randomness with sequential quantum measurements
• Simulating quantum instruments with projective measurements and quantum post-processing
• Semi-device-independent certification of quantum non-Markovianity using sequential Random Access Codes
• Optimal quantum violations of n-locality inequalities with conditional dependence on inputs
• Security of Device-independent Quantum Key Distribution under Sequential Attack
• Uncertainty-disturbance relations and applications