Quantum computing in optical microtraps based on the motional states of neutral atoms

Abstract

We investigate quantum computation with neutral atoms in optical microtraps where the qubit is implemented in the motional states of the atoms, i.e., in the two lowest vibrational states of each trap. The quantum gate operation is performed by adiabatically approaching two traps and allowing tunneling and cold collisions to take place. We demonstrate the capability of this scheme to realize a square root of swap gate, and address the problem of double occupation and excitation to other unwanted states. We expand the two-particle wave function in an orthonormal basis and analyze quantum correlations throughout the whole gate process. Fidelity of the gate operation is evaluated as a function of the degree of adiabaticity in moving the traps. Simulations are based on rubidium atoms in state-of-the-art optical microtraps with quantum gate realizations in the few tens of milliseconds duration range.

Holographic generation of microtrap arrays for single atoms by use of a programmable phase modulator

“…For example, qubit encoding on the motional state of an atom in a dipole trap was proposed in Ref. 9. In another scheme 8 the qubit is encoded in the motional state of one atom, which can be trapped in either of two traps with an adjustable separation.…”

“…In another scheme 8 the qubit is encoded in the motional state of one atom, which can be trapped in either of two traps with an adjustable separation. Both proposals 8,9 were studied for rubidium microdipole traps for which single-atom storage was obtained with our setup. According to these proposals single-qubit operations could be achieved by moving the traps adiabatically and bringing them closer so that tunneling between the two wells is allowed, and two-qubit operations are achieved by collisions between two atoms stored in distinct traps.…”

“…Schemes for quantum gates for neutral atoms have been theoretically proposed that rely on dipole-dipole interactions [2][3][4][5] or controlled collisions. [6][7][8][9] Such schemes can be implemented in optical lattices with a controlled filling factor, as shown in Ref. 10, where multiparticle entanglement by means of controlled collisions was demonstrated.…”

Quantum logic via optimal control in holographic dipole traps

“…A qubit can be encoded in the internal or motional state of an atom, and several qubits can be entangled using atom-light interactions or atom-atom interactions. Schemes for quantum gates for neutral atoms have been theoretically proposed, that rely on dipole-dipole interactions [2,3,4,5] or controlled collisions [6,7,8,9]. Such schemes can be implemented in optical lattices with a controlled filling factor, as shown in ref.…”

Micro traps for quantum information processing and precision force sensing

“…(3) Flexible quantum gates: in recent years, several promising candidates for the implementation of 2-qubit quantum gates for neutral atoms have been developed. Examples include gates based on the phase shift during ultra-cold collisions [30], on tunnelling processes depending on the motional states of atoms [6,11], on dipole-dipole interactions between atoms in high-lying Rydberg states [31], and on the coupling of atoms via the radiation field of optical or microwave resonators [53,55]. Common to all these schemes is that the interaction process is acting only during the gate operation and typically is independent of the mechanism for atom trapping.…”