I will describe recent experiments with superconducting circuits [1], in which the coherent coupling of a single photon to a quantum two-level system has been realized for the first time. In our approach, a Cooper-pair box, acting as a tunable artificial atom, interacts strongly with photons confined in a one-dimensional cavity formed by a transmission line resonator. When the Cooper-pair box qubit is tuned into resonance with the cavity, we observe the vacuum Rabi splitting of the cavity mode. This indicates that strong coupling, a condition previously only realizable in atomic cavity quantum electrodynamics experiments, is attained in this solid state system, and that coherent superpositions between the qubit and a single photon are generated. Detuning the qubit from the cavity resonance, we demonstrate high-fidelity dispersive quantum non-demolition readout of the qubit state. Using this technique, we have characterized the qubit properties spectroscopically, coherently manipulated the qubit state, and attained coherence times greater than 500 ns, indicating that this architecture is extremely attractive for quantum computing and control [2].
[1] A. Wallraff, D. I. Schuster, A. Blais, L. Frunzio, R.-S. Huang, J. Majer, S. Kumar, S. M. Girvin and R. J. Schoelkopf Nature (London) 431, 162 (2004).
[2] A. Blais, R.-S. Huang, A. Wallraff, S. M. Girvin and R. J. Schoelkopf Phys. Rev. A 69, 062320 (2004).
I will describe recent experiments with superconducting circuits [1], in which the coherent coupling of a single photon to a quantum two-level system has been realized for the first time. In our approach, a Cooper-pair box, acting as a tunable artificial atom, interacts strongly with photons confined in a one-dimensional cavity formed by a transmission line resonator. When the Cooper-pair box qubit is tuned into resonance with the cavity, we observe the vacuum Rabi splitting of the cavity mode. This indicates that strong coupling, a condition previously only realizable in atomic cavity quantum electrodynamics experiments, is attained in this solid state system, and that coherent superpositions between the qubit and a single photon are generated. Detuning the qubit from the cavity resonance, we demonstrate high-fidelity dispersive quantum non-demolition readout of the qubit state. Using this technique, we have characterized the qubit properties spectroscopically, coherently manipulated the qubit state, and attained coherence times greater than 500 ns, indicating that this architecture is extremely attractive for quantum computing and control [2].
[1] A. Wallraff, D. I. Schuster, A. Blais, L. Frunzio, R.-S. Huang, J. Majer, S. Kumar, S. M. Girvin and R. J. Schoelkopf Nature (London) 431, 162 (2004).
[2] A. Blais, R.-S. Huang, A. Wallraff, S. M. Girvin and R. J. Schoelkopf Phys. Rev. A 69, 062320 (2004).
