Experimental Sharing of Nonlocality among Multiple Observers with One Entangled Pair via Optimal Weak Measurements

Bell nonlocality plays a fundamental role in quantum theory. Numerous tests of the Bell inequality have been reported since the ground-breaking discovery of the Bell theorem.Up to now, however, most discussions of the Bell scenario have focused on a single pair of entangled particles distributed to only two separated observers. Recently, it has been shown surprisingly that multiple observers can share the nonlocality present in a single particle from an entangled pair using the method of weak measurements [Phys. Rev. Lett. {\bf 114}, 250401 (2015)]. Here we report an observation of double CHSH-Bell inequality violations for a single pair of entangled photons with strength continuous-tunable optimal weak measurements in photonic system for the first time. Our results not only shed new light on the interplay between nonlocality and quantum measurements but may also be significant for important applications such as unbounded randomness certification and quantum steering.

[1]  E. Knill,et al.  A strong loophole-free test of local realism , 2015, 2016 Conference on Lasers and Electro-Optics (CLEO).

[2]  S. Wehner,et al.  Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometres , 2015, Nature.

[3]  Paolo Villoresi,et al.  Three-observer Bell inequality violation on a two-qubit entangled state , 2016, 1611.02430.

[4]  J. Bell.  On the Einstein-Podolsky-Rosen paradox , 1964 .

[5]  N. Gisin,et al.  Quantum cryptography , 1998 .

[6]  3 SPCM Launcher HWP PBD HWP HWP PBS Filter Coupler PBD SPCM Processor Type-I BiBO Sandwich HWP QWP PBS Filter Slit φ Temporal , 2011 .

[7]  Guang-Can Guo,et al.  Optical realization of quantum gambling machine , 2000, quant-ph/0001008.

[8]  J. Lundeen,et al.  Procedure for direct measurement of general quantum states using weak measurement. , 2011, Physical review letters.

[9]  G. Roger,et al.  Experimental Test of Bell's Inequalities Using Time- Varying Analyzers , 1982 .

[10]  B. S. Cirel'son.  Quantum generalizations of Bell's inequality , 1980 .

[11]  Nicolas Gisin,et al.  Multiple Observers Can Share the Nonlocality of Half of an Entangled Pair by Using Optimal Weak Measurements. , 2014, Physical review letters.

[12]  R. Werner,et al.  Observation of one-way Einstein–Podolsky–Rosen steering , 2012, Nature Photonics.

[13]  Aaron J. Miller,et al.  Detection-loophole-free test of quantum nonlocality, and applications. , 2013, Physical review letters.

[14]  H. Weinfurter,et al.  Violation of Bell's Inequality under Strict Einstein Locality Conditions , 1998, quant-ph/9810080.

[15]  J. Lundeen,et al.  Direct measurement of the quantum wavefunction , 2011, Nature.

[16]  Benni Reznik,et al.  Revisiting Hardy's Paradox: Counterfactual Statements, Real Measurements, Entanglement and Weak Values , 2001 .

[17]  Guang-Can Guo,et al.  Phase estimation with weak measurement using a white light source. , 2013, Physical review letters.

[18]  A. Shimony,et al.  Proposed Experiment to Test Local Hidden Variable Theories. , 1969 .

[19]  J. Bell,et al.  Speakable and Unspeakable in Quantum Mechanics: Preface to the first edition , 2004 .

[20]  H. Weinfurter,et al.  Heralded Entanglement Between Widely Separated Atoms , 2012, Science.

[21]  Sharing of Nonlocality of a Single Member of an Entangled Pair of Qubits Is Not Possible by More than Two Unbiased Observers on the Other Wing , 2016 .

[22]  Erik Lucero,et al.  Violation of Bell's inequality in Josephson phase qubits , 2009, Nature.

[23]  Vaidman,et al.  How the result of a measurement of a component of the spin of a spin-1/2 particle can turn out to be 100. , 1988, Physical review letters.

[24]  Florian J. Curchod,et al.  Unbounded randomness certification using sequences of measurements , 2015, 1510.03394.

[25]  A C Doherty,et al.  Steering, entanglement, nonlocality, and the Einstein-Podolsky-Rosen paradox. , 2007, Physical review letters.

[26]  V. Scarani,et al.  The security of practical quantum key distribution , 2008, 0802.4155.

[27]  Yan Li,et al.  CW-pumped telecom band polarization entangled photon pair generation in a Sagnac interferometer. , 2015, Optics express.

[28]  A. Zeilinger,et al.  Bell violation using entangled photons without the fair-sampling assumption , 2012, Nature.

[29]  Matison,et al.  Experimental Test of Local Hidden-Variable Theories , 1972 .

[30]  D. Matsukevich,et al.  Bell inequality violation with two remote atomic qubits. , 2008, Physical review letters.

[31]  Albert Einstein,et al.  Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? , 1935 .

[32]  J. Neumann.  Mathematical Foundations of Quantum Mechanics , 1955 .