Preserving entanglement during weak measurement demonstrated with a violation of the Bell–Leggett–Garg inequality
| Autor: | James Wenner, Alexander N. Korotkov, Brooks Campbell, Io-Chun Hoi, Theodore White, Daniel Sank, Julian Kelly, Zijun Chen, Amit Vainsencher, Josh Mutus, John M. Martinis, A. Megrant, Justin Dressel, Peter O'Malley, Evan Jeffrey, Benjamin Chiaro, Charles Neill, Yu Chen, Andrew Dunsworth, Rami Barends, Pedram Roushan |
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| Rok vydání: | 2016 |
| Předmět: |
Physics
Bell state Computer Networks and Communications Statistical and Nonlinear Physics Quantum entanglement 01 natural sciences 010305 fluids & plasmas Computational Theory and Mathematics Quantum state Quantum mechanics Qubit 0103 physical sciences Computer Science (miscellaneous) Weak measurement Quantum information 010306 general physics Leggett–Garg inequality Quantum computer |
| Zdroj: | npj Quantum Information. 2 |
| ISSN: | 2056-6387 |
| DOI: | 10.1038/npjqi.2015.22 |
| Popis: | Weak measurement has provided new insight into the nature of quantum measurement, by demonstrating the ability to extract average state information without fully projecting the system. For single-qubit measurements, this partial projection has been demonstrated with violations of the Leggett–Garg inequality. Here we investigate the effects of weak measurement on a maximally entangled Bell state through application of the Hybrid Bell–Leggett–Garg inequality (BLGI) on a linear chain of four transmon qubits. By correlating the results of weak ancilla measurements with subsequent projective readout, we achieve a violation of the BLGI with 27 s.d.s. of certainty. Scientists in the US have developed a method to evaluate the properties of complex quantum states without causing their destruction. A team at the University of California Santa Barbara led by John Martinis verified that the properties of entangled quantum states can be probed using weak measurements. By extracting only small parts of quantum information in a single measurement, weak measurements avoid the problem whereby quantum states are destroyed when the information contained in them is measured. Although this has been successfully demonstrated for single quantum states, it remained unclear if weak measurements were compatible with more complicated entangled systems. By implementing an experimental test that verifies with high accuracy the preservation of those entangled states in measurements, the researchers have made it possible to probe the properties of qubits in complex quantum computing schemes. |
| Databáze: | OpenAIRE |
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