News & Events

  • Readout of Spin Qubits in Si/SiGe Quantum Dots Using a Cavity Embedded Cooper Pair Transistor

    April 1, 2014

    Spin qubits in Si/SiGe quantum dots are expected to enjoy very long coherence times, due to the weak interaction of the spins with their environment. The same weakness of interaction makes it difficult to determine the state of the qubits, and to transfer the quantum information they contain to other devices. In this project, we plan to use a superconducting device, the Cooper pair transistor, as a charge-tunable inductance that influences the resonant frequency of a superconducting microwave cavity.

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  • Measurement of Single Phonons with Single Photons

    April 1, 2014

    There has been great recent progress in controlling the quantum behavior of nanomechanical resonators. In this project, we aim to extend such control to the strongly quantum regime in which a single photon can be used to either read out or act back on a single phonon. To do so, we will use a superconducting device, the Cooper pair transistor, as a charge-tunable inductance embedded in a superconducting microwave cavity. By coupling the transistor to a nanomechanical resonator, we plan to use resonator motion at the level of a single phonon to shift the resonant frequency of the cavity.

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  • Generation of Quantum States of Light with a Josephson Laser

    April 1, 2014

    Quantum states of light are a topic of considerable current interest, and may lead to use of continuous variables for quantum information processing, as well as to quantum-enhanced measurements. Ideally, one would like to be able to generate such states simply, and to have the states contain large numbers of photons. We have recently developed a device, the cavity-embedded Cooper pair transistor, that uses the ac Josephson effect to inject large numbers of microwave photons into a cavity.

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  • Quantum-Classical Correspondence for Strongly Nonlinear, Circuit QED Based Systems

    April 1, 2014

    We are investigating the quantum versus classical dynamics involving tunneling Cooper-pairs in self-oscillating superconducting Josephson devices that are strongly interacting with microwave cavity photons. Manifest quantum states comprising large numbers of microwave photons result for such devices. This project provides theoretical support for experiments being carried out by Alex Rimberg's group. FACULTY CONTACT: Miles Blencowe

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  • Gravitationally Induced Decoherence

    April 1, 2014

    We are investigating the role that gravity plays as an environment in causing the rapid decoherence of matter superposition states. Our approach is based on the viewpoint that the standard perturbative quantization of general relativity provides an effective description of quantum gravity that is valid at ordinary energies. FACULTY CONTACT: Miles Blencowe

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