2 research outputs found
Generation of 3-Dimensional graph state with Josephson charge qubits
On the basis of generations of 1-dimensional and 2-dimensional graph states,
we generate a 3-dimensional N3-qubit graph state based on the Josephson charge
qubits. Since any two charge qubits can be selectively and effectively coupled
by a common inductance, the controlled phase transform between any two-qubit
can be performed. Accordingly, we can generate arbitrary multi-qubit graph
states corresponding to arbitrary shape graph, which meet the expectations of
various quantum information processing schemes. All the devices in the scheme
are well within the current technology. It is a simple, scalable and feasible
scheme for the generation of various graph states based on the Josephson charge
qubits.Comment: 4 pages, 4 figure
Efficient and long-lived quantum memory with cold atoms inside a ring cavity
Quantum memories are regarded as one of the fundamental building blocks of
linear-optical quantum computation and long-distance quantum communication. A
long standing goal to realize scalable quantum information processing is to
build a long-lived and efficient quantum memory. There have been significant
efforts distributed towards this goal. However, either efficient but
short-lived or long-lived but inefficient quantum memories have been
demonstrated so far. Here we report a high-performance quantum memory in which
long lifetime and high retrieval efficiency meet for the first time. By placing
a ring cavity around an atomic ensemble, employing a pair of clock states,
creating a long-wavelength spin wave, and arranging the setup in the
gravitational direction, we realize a quantum memory with an intrinsic spin
wave to photon conversion efficiency of 73(2)% together with a storage lifetime
of 3.2(1) ms. This realization provides an essential tool towards scalable
linear-optical quantum information processing.Comment: 6 pages, 4 figure