Cavity quantum electrodynamics (CQED) has been shown to be suitable to quantum computation processing1 thanks to the high quality factors Q of cavities, control of atom-cavity interactions and long lifetimes of Rydberg atoms2. In this context, the information can be stored and processed by atoms and photons representing the quantum bits (qubits)3 and two approaches can be distinct: the “microwa...

A novel setup for investigations in cavity quantum electrodynamics is described, which combines an optical microcavity Ž 5. 85 finesse 4.3=10 with an atomic Rb fountain, allowing full control over density and velocity of atoms entering the optical cavity. To demonstrate this point we study the temporal width of the transmission drops if slow single atoms pass through the cavity. We observe abso...

We show how to use two-mode squeezed light to exponentially enhance cavity-based dispersive qubit measurement. Our scheme enables true Heisenberg-limited scaling of the measurement, and crucially, it is not restricted to small dispersive couplings or unrealistically long measurement times. It involves coupling a qubit dispersively to two cavities and making use of a symmetry in the dynamics of ...

Abstract: We investigate the dynamics of a current-biased Josephson junction quantum bit or “qubit” coupled to an LC resonator. The Hamiltonian of this superconductor-based system is developed and the energies and eigen-functions of the entangled states are studied by Harmonic approximation. Since such a superconducting junction behaves as a two-level artificial atom coupled to a harmonic oscil...

Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits...