Quantum computation with atomic ensembles

Feng Mei, Mang Feng, Ya‐Fei Yu +1 more

We present a scheme for scalable quantum information processing with atomic ensembles and flying photons. Using the Rydberg blockade, we encode the qubits in the collective atomic states, which could be manipulated fast and easily due to the enhanced interaction in comparison to the single-atom case. We demonstrate that our proposed gating could be applied to generation of two-dimensional cluster states for measurement-based quantum computation. Moreover, the atomic ensembles also function as quantum repeaters useful for long-distance quantum state transfer. We show the possibility of our scheme to work in bad cavity or in weak coupling regime, which could much relax the experimental requirement. The efficient coherent operations on the ensemble qubits enable our scheme to be switchable between quantum computation and quantum communication using atomic ensembles.

Kazem Mahdavi, Deborah Koslover

Tim Byrnes, Ebubechukwu O. Ilo-Okeke

In this final chapter, we focus more on quantum information and quantum computing applications of atomic ensembles. We first examine ways of implementing continuous variables in quantum information processing using atomic ensembles, based on the Holstein--Primakoff approximation. Methods to perform quantum teleportation using this method, and some seminal experiments using this approach are introduced. We then introduce other approaches not based on the Holstein--Primakoff approximation to represent quantum information, namely the spinor quantum computing scheme. After showing a simple example of how such a scheme works with Deutsch's algorithm, we describe how adiabatic quantum computing can be performed, which displays the key feature of quantum error suppression.

Joshua Nunn

Mikhail D. Lukin, Axel André, M. A. Eisaman +5 more

Hui Yan, Yang Guo-Qing, Tao Shi +2 more

We propose a scheme for implementing quantum computation with atomic ensembles on an atom chip, where a single qubit is carried by an atomic ensemble instead of a single atom. Two electronic ground states of the atoms are involved, one state with one or no atom is used to represent the qubit and the other state is used to hold the residual atoms. One and two-qubit gates are implemented by internal state transition with laser pulse sequences in the presence of the exciting blockade mechanism. A scalable quantum computer can be realized by one-dimensional or two-dimensional atomic lattices on an atom chip.