Observation of Dicke superradiance for two artificial atoms in a cavity with high decay rate

An individual excited two-level system decays to its ground state in a process known as spontaneous emission. The probability of detecting the emitted photon decreases exponentially with the time passed since its excitation. In 1954, Dicke first considered the more subtle situation in which two emitters decay in close proximity to each other. He argued that the emission dynamics of a single two-level system is altered by the presence of a second one, even if it is in its ground state. Here, we present a close to ideal realization of Dicke's original two-spin Gedankenexperiment, using a system of two individually controllable superconducting qubits weakly coupled to a fast decaying microwave cavity. The two-emitter case of superradiance is explicitly demonstrated both in time-resolved measurements of the emitted power and by fully reconstructing the density matrix of the emitted field in the photon number basis.

[1]  Detlef Hommel,et al.  Superradiance of quantum dots , 2007 .

[2]  H. Carmichael,et al.  Single-atom cavity-enhanced absorption. I. Photon statistics in the bad-cavity limit , 1988 .

[3]  S. Girvin,et al.  Wiring up quantum systems , 2008, Nature.

[4]  C. Emary,et al.  Phase transitions and dark-state physics in two-color superradiance , 2011, 1109.2456.

[5]  R. H. Lehmberg,et al.  Radiation from an N-Atom System. I. General Formalism , 1970 .

[6]  R. Brecha,et al.  Cavity Induced Transparency , 1996 .

[7]  S. Girvin,et al.  Charge-insensitive qubit design derived from the Cooper pair box , 2007, cond-mat/0703002.

[8]  J. Marangos,et al.  Electromagnetically induced transparency : Optics in coherent media , 2005 .

[9]  D. Porras,et al.  Mesoscopic entanglement induced by spontaneous emission in solid-state quantum optics. , 2012, Physical review letters.

[10]  F. Schmidt-Kaler,et al.  Light interference from single atoms and their mirror images , 2001, Nature.

[11]  A. Wallraff,et al.  Characterizing Quantum Microwave Radiation and its Entanglement with Superconducting Qubits , 2012, 1206.3405.

[12]  Morin,et al.  Vacuum Rabi splitting as a feature of linear-dispersion theory: Analysis and experimental observations. , 1990, Physical review letters.

[13]  S. Maniscalco,et al.  Dicke model and environment-induced entanglement in ion-cavity QED , 2009, 0907.0778.

[14]  Barry C. Sanders,et al.  Photon-Mediated Interactions Between Distant Artificial Atoms , 2013, Science.

[15]  C. Fabre,et al.  Collective Absorption of Blackbody Radiation by Rydberg Atoms in a Cavity: An Experiment on Bose Statistics and Brownian Motion , 1982 .

[16]  R. Brewer,et al.  Observation of superradiant and subradiant spontaneous emission of two trapped ions , 1996, Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference.

[17]  Ulrike Woggon,et al.  Photon statistics in the cooperative spontaneous emission. , 2009, Optics express.

[18]  J. Dowling.  Exploring the Quantum: Atoms, Cavities, and Photons. , 2014 .

[19]  M. Feld,et al.  Observation of Dicke Superradiance in Optically Pumped HF Gas , 1973 .

[20]  J. Twamley,et al.  Superradiance and phase multistability in circuit quantum electrodynamics , 2010, 1007.2231.

[21]  Andreas Wallraff,et al.  Multimode mediated qubit-qubit coupling and dark-state symmetries in circuit quantum electrodynamics , 2011 .

[22]  K. Mølmer,et al.  Measurement-induced two-qubit entanglement in a bad cavity: Fundamental and practical considerations , 2012, 1202.4854.

[23]  G. Milburn,et al.  Entanglement in the steady state of a collective-angular-momentum (Dicke) model , 2002 .

[24]  Barry C. Sanders,et al.  Input-output theory for waveguide QED with an ensemble of inhomogeneous atoms , 2013, 1305.7135.

[25]  H. Carmichael.  Statistical Methods in Quantum Optics 2: Non-Classical Fields , 2007 .

[26]  Heinzen,et al.  Vacuum radiative level shift and spontaneous-emission linewidth of an atom in an optical resonator. , 1987, Physical review letters.

[27]  R. Lehmberg.  Radiation from an N-Atom System. II. Spontaneous Emission from a Pair of Atoms , 1970 .

[28]  C. Fabre,et al.  Observation of Near-Infrared Dicke Superradiance on Cascading Transitions in Atomic Sodium , 1976 .

[29]  R. Dicke.  Coherence in Spontaneous Radiation Processes , 1954 .

[30]  R. Bonifacio,et al.  Quantum Statistical Theory of Superradiance. II , 1971 .

[31]  Andreas Wallraff,et al.  Time Resolved Collective Entanglement Dynamics in Cavity Quantum Electrodynamics , 2012 .

[32]  A. Wallraff,et al.  Controlling the dynamic range of a Josephson parametric amplifier , 2013, 1305.6583.

[33]  Ralf Röhlsberger,et al.  Collective Lamb Shift in Single-Photon Superradiance , 2010, Science.

[34]  Serge Haroche,et al.  Superradiance: An essay on the theory of collective spontaneous emission , 1982 .

[35]  Y. N. Chen,et al.  Proposal for teleportation of charge qubits via super-radiance , 2005, cond-mat/0502412.