Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session A27: Focus Session: Quantum Optics with Superconducting Circuits I |
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Sponsoring Units: GQI Chair: Jay Gambetta, University of Waterloo Room: C155 |
Monday, March 21, 2011 8:00AM - 8:12AM |
A27.00001: Quantum temperature of a modulated oscillator: spectral signatures Mark Dykman, Michael Marthaler, Vittorio Peano Relaxation of a quantum system is usually due to emission of excitations of a thermal reservoir. The emission events happen at random. For periodically modulated systems, the corresponding noise leads to a finite-width distribution over the quasi-energy (Floquet) states. It can be characterized by an effective nonzero quantum temperature even where the temperature of the reservoir is zero. We show that, as a result, the spectra of fluctuations and response of a parametrically modulated underdamped nonlinear oscillator can display a fine structure. The form of the spectra sensitively depends on the temperature of the reservoir. [Preview Abstract] |
Monday, March 21, 2011 8:12AM - 8:24AM |
A27.00002: Switching in modulated quantum oscillators beyond the rotating wave approximation. Vittorio Peano, Michael Marthaler, Mark Dykman Experiments with Josephson bifurcation amplifiers have reached the regime where the switching between different metastable states is governed by quantum fluctuations [1]. The existing theoretical analysis of the metastable decay relies on the rotating wave approximation (RWA) and gives an exponentially small switching rate [2]. Therefore if corrections to the RWA modify the switching rate, they can become substantial even where they are small. We incorporate them within a semiclassical perturbation theory in the Floquet basis. Our analytical results are corroborated by numerical calculations and suggest a switching mechanism that had been previously overlooked. \\[4pt] [1] R. Vijay et al, Rev. Sci. Instr. 80, 111101 (2009). \\[0pt] [2] M. I. Dykman and V. N. Smelyanskii, Sov. Phys. JETP 67, 1769 (1988); M. Marthaler and M. I. Dykman, Phys. Rev. A 73, 42108 (2006). [Preview Abstract] |
Monday, March 21, 2011 8:24AM - 8:36AM |
A27.00003: Many-body effects of quantum impurity models via circuit QED Prasenjit Dutt, Michel Devoret, Karyn Le Hur Circuit QED systems serve as an ideal quantum simulator of condensed matter models, given the great degree of experimental precision and control with which they can be manipulated. Quantum impurity models exhibiting renormalization and confinement ideas reminiscent of QCD, can be realized in circuits comprising superconducting qubits and long transmission lines, which play the role of macroscopic bosonic baths. In particular, it is possible to use such systems to engineer standard low energy many-body Hamiltonians such as the spin-boson or anisotropic Kondo model. We develop a framework combining input-output theory and many-body techniques to study correlated photon transport and specifically the qubit response in such circuits. [Preview Abstract] |
Monday, March 21, 2011 8:36AM - 8:48AM |
A27.00004: Autoresonant vs. ladder climbing response in a superconducting Josephson phase circuit Nadav Katz, Yaara Rofe, Yoni Shalibo, Radoslaw Bialczak, John Martinis, Ido Barth, Lazar Friedland Anharmonic oscillators exhibit a unique response to a chirped drive, referred to as either autoresonance or ladder climbing. This typically involves a bifurcation of the oscillation amplitude depending both on the strength of the drive and on the system's anharmonicity. In this parameter space, the threshold of bifurcation exhibits a transition between sequential state excitation (quantum ladder climbing) and the population of coherent-like states (classical autoresonance). Previous attempts to experimentally map this transition have only been possible in either classical or quantum conditions. Superconducting Josephson phase circuits enable us to map these two regimes, including the intermediate regime, due to their tunable anharmonicity. We measure the bifurcation phenomena in this system over the relevant parameter space where the transition is observed. We compare to numerical simulations and theoretical analysis. [Preview Abstract] |
Monday, March 21, 2011 8:48AM - 9:00AM |
A27.00005: Quantum Transport of Strongly-Correlated Photons in Waveguide QED Huaixiu Zheng, Daniel J. Gauthier, Harold U. Baranger We present an exact solution of the quantum transport problem of multi-mode photons in a waveguide quantum electrodynamics (QED) system, which may be realized in a variety of circuit-QED, plasmonic, photonic, or cold-atom contexts. The bosonic modes are strongly coupled to a local atomic or qubit system, which can be a two-level, Gamma-type three-level, or N-type four-level system. We show that strong coupling produces dramatic quantum optics effects. In particular, multi-photon bound states emerge in the scattering of two or more photons. Such bound states have a large impact on the transport of coherent-state wave-packets. For a two-level system, the single-photon probability is suppressed while multi-photon probabilities are strongly enhanced, resulting in non-classical statistics. For a three-level system, as one tunes the coupling strength and the control field, the transmitted light can show bunching or antibunching, indicating effective attractive or repulsive interactions. Finally, for a N-type four-level system, we demonstrate that the multi-photon components can be largely suppressed, leading to a potential single-photon filter. [Preview Abstract] |
Monday, March 21, 2011 9:00AM - 9:12AM |
A27.00006: Superradiance and Phase Multistability in Circuit Quantum Electrodynamics Michael Delanty, Stojan Rebic, Jason Twamley By modelling the coupling of multiple superconducting qubits to a single cavity in the circuit-quantum electrodynamics (QED) framework we find that it should be possible to observe superradiance and phase multistability using currently available technology (M. Delanty, S. Rebi\'c and J. Twamley, arxiv:1007.2231). Due to the exceptionally large couplings present in circuit-QED we predict that superradiant microwave pulses should be observable with only a very small number of qubits (just three or four), in the presence of energy relaxation and small differences in the qubit-field coupling strengths. This paves the way for circuit-QED implementations of superradiant state readout and decoherence free subspace state encoding in subradiant states. The system considered here also exhibits phase multistability when driven with large field amplitudes, and this effect may have applications for collective qubit readout and for quantum feedback protocols. Furthermore, we extend our analysis to superradiance and collective effects in multi-resonator circuit-QED systems. [Preview Abstract] |
Monday, March 21, 2011 9:12AM - 9:24AM |
A27.00007: Design and Calibration of an Improved Josephson Parametric Amplifier William F. Kindel, Hsiang-Sheng Ku, Francois Mallet, Leila R. Vale, Gene C. Hilton, Kent D. Irwin, Konrad W. Lehnert Phase sensitive amplifiers are of interested because in principal they can amplify one quadrature of a tone without any added noise, unlike phase insensitive amplifiers which amplify both quadratures but must add half a quanta of noise. In situations where a signal of interest is encoded in the modulation of only one quadrature of a tone, phase sensitive detection is clearly dvantageous. With the goal of creating a microwave-frequency phase-sensitive amplifier that adds no noise, we will present the design and performance of a recently tested Josephson Parametric Amplifier (JPA). Initial measurements indicate that the JPAs added noise is no greater than 0.1 quanta. This is a substantial improvement over a previous design for which the added noise was 0.3 quanta [1]. I will discuss changes made to the design and possible reason for the improvement. \\[4pt] [1] M. A. Castellanos-Beltran et al, Nature Phys. 4 929 (2008). M. A. Castellanos-Beltran [Preview Abstract] |
Monday, March 21, 2011 9:24AM - 9:36AM |
A27.00008: Parametric processes in a cavity resonator terminated with a DC-SQUID Francois Nguyen, Eva Zakka Bajjani, Minhyea Lee, Lafe Spietz, Leila Vale, Raymond Simmonds, Jose Aumentado The coplanar waveguide resonators with SQUIDs have become common to several recent superconducting quantum information experiments. In this talk, we will present some recent results which demonstrate the manipulation of the internal harmonic modes of a microwave cavity resonator using a flux-driven SQUID as a parametric mode mixing resource. [Preview Abstract] |
Monday, March 21, 2011 9:36AM - 9:48AM |
A27.00009: Quantum non-demolition measurement of microwave photons in superconducting circuits using engineered quadratic interactions Chunqing Deng, Jay Gambetta, Adrian Lupascu We present a quantum electrical circuit with Josephson junctions formed by two anharmonic oscillators coupled with an interaction of the form $g\gamma_1^2\gamma_2^2$ where $\gamma_1$ and $\gamma_2$ are position-like coordinates. This type of coupling allows the quantum non-demolition measurement of the energy of one oscillator by monitoring the frequency of the second oscillator. We find that the optimized coupling strength $g$ scales as $\sqrt{\omega_1 \omega_2}/\sqrt{n_1 n_2}$, with $\omega_{1,2}$ the frequency, and $n_{1,2}$ the maximum photon storage capacity of each resonator. With an optimized coupling, it is possible to achieve high fidelity detection of up to 10 photons over a time of the order of microseconds. We discuss the possibility of observing quantum jumps in the number of photons and related applications. We also present our experimental work on the implementation of this detection scheme. C. Deng, J. M. Gambetta, and A. Lupascu, arXiv:1008.3363 (2010). [Preview Abstract] |
Monday, March 21, 2011 9:48AM - 10:00AM |
A27.00010: Lossless on-chip microwave circulator using Josephson parametric converters Baleegh Abdo, Archana Kamal, Michael Hatridge, Flavius Schackert, Kurtis Geerlings, Michel Devoret Motivated by our recent theoretical work on non-reciprocal parametric devices [1], we propose a novel scheme for realizing a four-port, lossless, on-chip microwave circulator using a compact design of Josephson parametric converters (JPC's) and hybrids. The JPC, which is normally used as a phase-preserving quantum-limited amplifier, is operated here in a pure conversion mode with unity photon gain. The non-reciprocity of the device is induced by a phase shift between the two pump signals feeding two JPC's sharing a common idler port. The non-reciprocity direction can thus be reversed much more rapidly than by changing a magnetic field. Furthermore, since the device consists only of purely dispersive components, the proposed circulator should not add any noise to signals it processes. \\[4pt] [1] A. Kamal, J. Clarke and M.H. Devoret, accepted by Nature Physics, arXiv:1010.1794 [Preview Abstract] |
Monday, March 21, 2011 10:00AM - 10:12AM |
A27.00011: Dynamic range and noise of the Josephson parametric converter Flavius Schackert, Baleegh Abdo, Michael Hatridge, Luigi Frunzio, Robert J. Schoelkopf, Michel H. Devoret We present recent progress in characterizing key properties of the Josephson parametric converter (JPC): its dynamic range and noise performance. The JPC is a phase-preserving parametric amplifier operating in the microwave regime. It is based on a ring of four Josephson junctions, which provides the non-linearity, coupled to~two microwave resonators, which increase the effective interaction between the incoming signal and this non-linearity. The JPC operates with a minimal number of modes, which simplifies its analysis, and is close to the ideal non-degenerate parametric amplifier operating at the quantum limit of noise. Besides having sufficient gain and bandwidth, a practical amplifier useful for e.g. the readout of superconducting qubits will need to exhibit a sufficiently low noise temperature and dynamic range. While dynamic range ensures that an incoming signal does not saturate the amplifier, a low noise temperature is necessary to minimally degrade signal-to-noise ratio.~ [Preview Abstract] |
Monday, March 21, 2011 10:12AM - 10:24AM |
A27.00012: Microwave Photon Counter Based on Josephson Junctions Y.-F. Chen, D. Hover, S. Sendelbach, L. Maurer, R. McDermott, S.T. Merkel, E.J. Pritchett, F.K. Wilhelm We describe a microwave photon counter based on current-biased Josephson junctions. The absorption of a single microwave photon causes a junction to switch to the voltage state, producing a large and easily measured classical signal. With a two-junction circuit, we have performed a microwave version of the Hanbury Brown and Twiss experiment at 4 GHz, and demonstrated a clear signature of photon bunching for a thermal source. The design is readily scalable to tens of parallelized junctions, a configuration that would allow number-resolved counting of microwave photons. We discuss possible applications to cavity state readout and to measurement of the counting statistics of microwave photons emitted by mesoscopic conductors. [Preview Abstract] |
Monday, March 21, 2011 10:24AM - 10:36AM |
A27.00013: Quantum Limited Amplification and Detection with a Non-Linear Cavity Detector Catherine Laflamme, Aashish Clerk A variety of recent experiments demonstrate the power of using driven microwave resonators for quantum measurement and amplification. Here, we consider theoretically the use of a driven cavity with a Kerr-type non-linearity to amplify a dispersively coupled signal. We consider the regime where there is no multi-stability in the cavity dynamics; this is similar to recent experiments.\footnote{M. Hatridge {\it et al.}, arXiv:1003.2466v1}$^,$\footnote{F.R. Ong {\it et al.}, arXiv:1010.6248v1} The amplifier quantum-limit in this case involves the physics of backaction, unlike the more studied `scattering' mode of operation. We calculate the added noise of this nonlinear cavity amplifier, and show that it exhibits universal scaling in the vicinity of the bifurcation point. We also show that for low frequencies the nonlinear cavity amplifier reaches the fundamental quantum limit on its noise temperature, but has large backaction - imprecision noise correlations. This implies that the non-linear cavity cannot be simply used for QND qubit measurement, but could have interesting applications to non-resonant force sensing. Our results have applications to quantum information processing, electromechanics and optomechanics. [Preview Abstract] |
Monday, March 21, 2011 10:36AM - 10:48AM |
A27.00014: A flux-driven Josephson parametric amplifier for experiments with propagating quantum microwaves E.P. Menzel, A. Baust, F. Deppe, T. Niemczyk, E. Hoffmann, M. Haeberlein, A. Marx, R. Gross, E. Solano, K. Inomata, T. Yamamoto, Y. Nakamura For the detection of propagating quantum microwaves in circuit QED linear amplifiers are key ingredients. Phase sensitive amplifiers [e.g., Josephson parametric amplifiers (JPA)] in principle allow for the amplification of one signal quadrature without adding noise. In practice, however, internal losses often introduce a finite amount of noise. We have recently shown that, despite such a residual noise, signals on the quantum level can be fully characterized using two amplification chains and suitable correlations [E.P. Menzel et al., PRL 105, 100401 (2010)]. In this work, we characterize a flux-driven JPA. At 5.64\,GHz the maximum degenerate gain is 25.5\,dB and the signal bandwidth is 1.8\,MHz. Phase-insensitive measurements yield a noise temperature of 100$\pm$20\,mK, which is below the standard quantum limit of 135\,mK. [Preview Abstract] |
Monday, March 21, 2011 10:48AM - 11:00AM |
A27.00015: Microstrip SQUID amplifiers at gigahertz frequencies M.P. DeFeo, P. Bhupathi, M. Ware, B.L.T. Plourde SQUID amplifiers based on the microstrip resonance formed between the input coil and SQUID washer have demonstrated substantial gain and low noise at frequencies of several hundred MHz. Operation at higher frequencies requires shorter input coils and the corresponding reduced mutual inductance must be compensated with an increased transfer function in order to avoid loss of gain. We have fabricated microstrip SQUID amplifiers using low capacitance Al-AlOx-Al submicron junctions and large resistive shunts to increase the transfer function while keeping the SQUID non-hysteretic. ~These devices have demonstrated gains beyond 20dB at frequencies in the gigahertz range. Gain and noise measurements as well as applications of these devices in the field of quantum information science will be discussed. [Preview Abstract] |
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