Robert Schoelkopf

TL;DR: While there are several candidate technologies for building a quantum computer, one of the most promising is superconducting quantum circuits, operated at cryogenic temperatures approaching 0.01 K.

TL;DR: In this paper, the spectrum of the output noise of Nb hot-electron mixers is measured and the dominant contribution to the noise is thermal fluctuation noise, which is expected to display a one pole rolloff.

TL;DR: In this article, the Radio Frequency Single Electron Transistor (RF-SET) was used as an ideal readout amplifier for high impedance detectors such as the STJ and photon-counting direct detectors.

Abstract: Submitted for the MAR12 Meeting of The American Physical Society Varying Cavity Quality Factor in situ for a Transmon in Circuit QED ANDREI PETRENKO, ADAM SEARS, GERHARD KIRCHMAIR, HANHEE PAIK, LUYAN SUN, GIANLUIGI CATELANI, LEONID GLAZMAN, ROBERT SCHOELKOPF, Yale University — Superconducting transmon qubits have recently been studied within 3D cavities. In addition to increasing the coherence times of the qubits this has enabled a simple scheme for varying the quality factor Q (or decay rate κ) of a cavity in situ. This decay rate plays an important role in our understanding of a number of effects in circuit quantum electrodynamics, many of which have direct bearing on qubit decoherence processes. Here we study how adjusting the cavity Q affects the coherence times of a single qubit within the 3D architecture. We demonstrate that varying the coupling enables us to not only examine the limitations of qubit T1 due to the Purcell Effect, but also probe new decoherence mechanisms such as the dephasing due to photon shot noise. By understanding and minimizing these effects, we obtain record coherences times T2 and TEcho 2 of ∼ 27μs and ∼ 47μs respectively. Andrei Petrenko Yale University Date submitted: 20 Nov 2011 Electronic form version 1.4

TL;DR: In this paper , a hybrid microwave/optical platform capable of coupling to bulk acoustic waves through cavity-enhanced piezoelectric and photoelastic interactions is presented, which achieves fully resonant and well-mode-matched interactions between a 3D microwave cavity, a high-frequency bulk acoustic resonator, and a Fabry Perot cavity.