Quantum information processing with a minimal control

Arnob Kumar Ghosh, Rubén Seoane Souto, Vahid Azimi Mousolou +2 more

Coherent quantum state transfer over macroscopic distances between non-neighboring elements in quantum circuits is a crucial component to increase connectivity and simplify quantum information processing. To facilitate such transfers, an efficient and easily controllable quantum pump would be highly beneficial. In this work, we demonstrate such a quantum pump based on a one-dimensional quasicrystal Fibonacci chain (FC). In particular, we utilize the unique properties of quasicrystals to pump the edge-localized winding states between the two distant ends of the chain by only minimal manipulation of the FC at its end points. We establish the necessary conditions for successful state transfer within a fully time-dependent picture and also demonstrate robustness of the transfer protocol against disorder. We then couple external qubits to each end of the FC and establish highly adaptable functionality as a quantum bus with both on-demand switching of the qubit states and generation of maximally entangled Bell states between the qubits. Thanks to the minimal control parameters, the setup is well-suited for implementation across diverse experimental platforms, thus establishing quasicrystals as an efficient platform for versatile quantum information processing.

John Edward Gough, V. P. Belavkin

Gershon Kurizki, Abraham G. Kofman

Sebastian Deffner

We study quantum information processing by means of optimal control theory. To this end, we analyze the damped Jaynes-Cummings model, and derive optimal control protocols that minimize the heating or energy dispersion rates, and controls that drive the system at the quantum speed limit. Special emphasis is put on analyzing the subtleties of optimal control theory for our system. In particular, it is shown how two fundamentally different approaches to the quantum speed limit can be reconciled by carefully formulating the problem.

Dongyang Wang, Yong Liu, Jiangfang Ding +8 more

Quantum entanglement enables measurement on one party to affect the other’s state. Based on this peculiar feature, we propose a model of remote-controlled quantum computing and design an optical scheme to realize this model for a single qubit. As an experimental demonstration of this scheme, we further implement three Pauli operators, Hardmard gate, phase gate, and π / 8 gate. The minimal fidelity obtained by quantum process tomography reaches 82%. Besides, as a potential application, our model contributes to secure remote quantum information processing.