Solid state multi-ensemble quantum computer in cavity quantum electrodynamics model

Abstract

The first realization of solid state quantum computer was demonstrated recently by using artificial atoms -transmons in superconducting resonator. Here, we propose a novel architecture of flexible and scalable quantum computer based on a waveguide circuit coupling many quantum nodes of controlled atomic ensembles. For the first time, we found the optimal practically attainable parameters of the atoms and circuit for 100% efficiency of quantum memory for multi qubit photon fields and confirmed experimentally the predicted perfect storage. Then we revealed self modes for reversible transfer of qubits between the quantum memory node and arbitrary other nodes. We found a realization of iSWAP gate via direct coupling of two arbitrary nodes with a processing rate accelerated proportionally to number of atoms in the node. A large number of the two-qubit gates can be simultaneously realized in the circuit for implementation of parallel quantum processing. Dynamic coherent elimination procedure of excess quantum state and collective blockade mechanism are proposed for realization of iSW AP and √ iSW AP quantum gates.

Photon echo quantum random access memory integration in a quantum computer

“…Thus, the quantum efficiency Q 1 can be very close to 100% for relatively large inhomogeneous broadening in in comparison with the quantum Rabi frequencies of the QM and processing nodes ( in > 0 and in > 1 ) as was shortly noted in [16] for QC on multi-atomic ensembles. The discussed properties of the optimal temporal self-modes reveal experimentally achievable coupling strength of QM and processing nodes in the QC scheme that somehow reminds us of the properties of optimal quantum storage processes studied recently in [35,36].…”

“…By using the described manipulations of the resonant frequencies of the QM and processing nodes as well as by exploiting the dephasing/rephasing processes of the atomic coherence in the QM node, one can also download the photon qubits in many processing nodes in order to realize a full table of protocols for quantum processing on the photonic qubits. In particular, we can perform basic single-and two-qubit gates by using physical encoding of a single logical qubit on two processing nodes with the controlled resonant coupling of the processing nodes through the interaction with the main and additional field modes of QED cavities as discussed in [16].…”

“…Recently we have proposed an efficient multi-qubit photon echo based QM (PEQM) in single mode QED resonator (cavity PEQM) [13,14,15]. Also, it was proposed in paper [16] without spectral matching condition.…”

“…Another related problem is the integration of the QM into QC for its effective coupling with processing gates and quantum communication with the external environment of the QC. Recently, we have proposed an efficient multi-qubit PEQM in a single-mode QED resonator (cavity PEQM) [14][15][16]. Also, it was proposed in [17] without a spectral matching condition.…”

Atomic quantum transistor based on swapping operation

“…Let us take that working frequencies of the atoms shifted from the frequency ω e of cavity field modes where we also assume equalized frequencies of the field modes ω kα = ω e (α = 1, 2 is an index of the modes, k α are wave vectors of the field modes). The effective Hamiltonian describing the process can be obtained by unitary transformation of initial James-Cummings model Hamiltonian that excludes non-resonant atomic-photon interaction in the first perturbation order [17,23]. This procedure yields the following Hamiltonian of the ME1 and ME2-nodes and gate-atom in a photon vacuum state:…”