Browsing by Author "Shringarpure, S.U."
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Item Destructive Controlled-Phase Gate Using Linear Optics(2021-03-05) Shringarpure, S.U.; Franson, J.D.Knill, Laflamme, and Milburn [Nature 409, 46 (2001)] showed that linear optics techniques could be used to implement a nonlinear sign gate. They also showed that two of their nonlinear sign gates could be combined to implement a controlled-phase gate, which has a number of practical applications. Here we describe an alternative implementation of a controlled-phase gate that only requires the use of a single nonlinear sign gate. This gives a much higher average probability of success when the required ancilla photons are generated using heralding techniques. This implementation of a controlled-phase gate destroys the control qubit, which is acceptable in a number of applications where the control qubit would have been destroyed in any event, such as in a postselection process.Item Generating photon-added states without adding a photon(The American Physical Society, 2019-10-02) Shringarpure, S.U.; Franson, J.D.We show that a continuous range of nonclassical states of light can be generated using conditional measurements on the idler mode of an optical parametric amplifier. The output state is prepared by introducing a coherent state in the signal mode of the amplifier with a single photon in the idler mode, followed by a conditional measurement of a single photon in the output idler mode. By varying the gain of the amplifier, this approach can produce a coherent state, a photon-added state, a displaced number state, or a continuous range of other nonclassical states with intermediate properties. We note that this approach can generate a photon-added state even though the postselected amplifier does not add any photons to the signal or idler modes. The ability to generate a continuous range of nonclassical states may have practical applications in quantum information processing.Item Generation of entangled cats from photon number states(OSA Publishing, 2020-09) Shringarpure, S.U.; Franson, J.D.A phase-entangled cat state is created when a number state passes through a beamsplitter. This entanglement is used to violate Bell’s inequality using large Kerr media. This approach may have applications in quantum communications.Item Violating Bell’s inequality using a number state and a beam splitter(American Physical Society, 2020-08-31) Shringarpure, S.U.; Franson, J.D.Passing a photon number state through a balanced beam splitter will produce an entangled state in which the phases of the two output modes are highly correlated. We show that Bell’s inequality can be violated using this entangled state and two distant interferometers. The output modes of the beam splitter can be viewed as a generalized form of an entangled Schrodinger cat state, which may have practical applications in quantum communications.