Abstract
By repeated trials, one can determine the fairness of a classical coin with a confidence which grows with the number of trials. A quantum coin can be in a superposition of heads and tails and its state is most generally a density matrix. Given a string of qubits representing a series of trials, one can measure them individually and determine the state with a certain confidence. We show that there is an improved strategy which measures the qubits after entangling them, which leads to a greater confidence. This strategy is demonstrated on the simulation facility of IBM quantum computers.
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Acknowledgement
The authors acknowledge the use of the ibmqx4 quantum computer and the IBM Q16 computer in Melbourne.
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Maitra, A., Samuel, J. & Sinha, S. Rapid communication Likelihood theory in a quantum world: Tests with quantum coins and computers. Pramana - J Phys 94, 57 (2020). https://doi.org/10.1007/s12043-020-1926-9
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DOI: https://doi.org/10.1007/s12043-020-1926-9