Quantum-optical control techniques for atomic motional states

The subject of this work is the control of the quantum mechanical motional state of trapped neutral Cesium atoms. This is accomplished using a rarely considered method based on microwave radiation in combination with a spin dependent optical lattice potential. The setup used was designed to trap and to store on the order of ten atoms in a one dimensional optical lattice. Fluorescence imaging allows to determine both, the number and the position of the atoms. The spin degree of freedom is manipulated using microwave radiation and the trapping potential allows to shift the atoms to the 'left' or to the 'right' along the potential axis, depending on their spin orientation. A microwave spectrum with a slightly displaced lattice exhibits sideband peaks corresponding to a change of the vibrational quantum number. This is the mechanism which introduces coupling between the spin and the motional degree of freedom. The work draws parallels to the usually used sideband technique based on optical transitions instead of microwaves and exploiting the photon recoil instead of a state dependent potential. Similar to the optical method the microwave based approach allows for the realization of a resolved-sideband cooling technique which efficiently prepares the atomic ensemble in the motional ground state. Starting from this purified quantum mechanical state, other interesting states are prepared using successive sideband transitions. The result of the preparation is probed by implementing filtering schemes for the motional state. With this control technique the experimental setup in total is capable to control the spin, the position along the one dimensional periodic potential and the vibrational state of the atoms.The subject of this work is the control of the quantum mechanical motional state of trapped neutral Cesium atoms. This is accomplished using a rarely considered method based on microwave radiation in combination with a spin dependent optical lattice potential. The setup used was designed to trap and to store on the order of ten atoms in a one dimensional optical lattice. Fluorescence imaging allows to determine both, the number and the position of the atoms. The spin degree of freedom is manipulated using microwave radiation and the trapping potential allows to shift the atoms to the 'left' or to the 'right' along the potential axis, depending on their spin orientation. A microwave spectrum with a slightly displaced lattice exhibits sideband peaks corresponding to a change of the vibrational quantum number. This is the mechanism which introduces coupling between the spin and the motional degree of freedom. The work draws parallels to the usually used sideband technique based on optical transitions instead of microwaves and exploiting the photon recoil instead of a state dependent potential. Similar to the optical method the microwave based approach allows for the realization of a resolved-sideband cooling technique which efficiently prepares the atomic ensemble in the motional ground state. Starting from this purified quantum mechanical state, other interesting states are prepared using successive sideband transitions. The result of the preparation is probed by implementing filtering schemes for the motional state. With this control technique the experimental setup in total is capable to control the spin, the position along the one dimensional periodic potential and the vibrational state of the atoms.

Oct 15, 20104 citations

Quantum Effects in Optical Control of Atomic Motion

Harold J. Metcalf

APSNov 1, 19960 citations

Demonstration of a quantum logic gate in a cryogenic surface-electrode ion trap

Shannon X. Wang, Jaroslaw Labaziewicz, Yufei Ge +2 more

We demonstrate quantum control techniques for a single trapped ion in a cryogenic, surface-electrode trap. A narrow optical transition of ${\mathrm{Sr}}^{+}$ along with the ground and first excited motional states of the harmonic trapping potential form a two-qubit system. The optical qubit transition is susceptible to magnetic field fluctuations, which we stabilize with a simple and compact method using superconducting rings. Decoherence of the motional qubit is suppressed by the cryogenic environment. ac Stark shift correction is accomplished by controlling the laser phase in the pulse sequencer, eliminating the need for an additional laser. Quantum process tomography is implemented on atomic and motional states by use of conditional pulse sequences. With these techniques, we demonstrate a Cirac-Zoller controlled-not gate in a single ion with a mean fidelity of $91(1)%$ .We demonstrate quantum control techniques for a single trapped ion in a cryogenic, surface-electrode trap. A narrow optical transition of ${\mathrm{Sr}}^{+}$ along with the ground and first excited motional states of the harmonic trapping potential form a two-qubit system. The optical qubit transition is susceptible to magnetic field fluctuations, which we stabilize with a simple and compact method using superconducting rings. Decoherence of the motional qubit is suppressed by the cryogenic environment. ac Stark shift correction is accomplished by controlling the laser phase in the pulse sequencer, eliminating the need for an additional laser. Quantum process tomography is implemented on atomic and motional states by use of conditional pulse sequences. With these techniques, we demonstrate a Cirac-Zoller controlled-not gate in a single ion with a mean fidelity of $91(1)%$.

arXiv:0912.4892Physical Review AJun 24, 201035 citations

Quantum Control in Atom Optics

Dan Steck

APSApr 1, 20050 citations

Optimal control of atom transport for quantum gates in optical lattices

Gabriele De Chiara, Tommaso Calarco, Marco Anderlini +5 more

By means of optimal control techniques we model and optimize the manipulation of the external quantum state (center-of-mass motion) of atoms trapped in adjustable optical potentials. We consider in detail the cases of both noninteracting and interacting atoms moving between neighboring sites in a lattice of a double-well optical potentials. Such a lattice can perform interaction-mediated entanglement of atom pairs and can realize two-qubit quantum gates. The optimized control sequences for the optical potential allow transport faster and with significantly larger fidelity than is possible with processes based on adiabatic transport.By means of optimal control techniques we model and optimize the manipulation of the external quantum state (center-of-mass motion) of atoms trapped in adjustable optical potentials. We consider in detail the cases of both noninteracting and interacting atoms moving between neighboring sites in a lattice of a double-well optical potentials. Such a lattice can perform interaction-mediated entanglement of atom pairs and can realize two-qubit quantum gates. The optimized control sequences for the optical potential allow transport faster and with significantly larger fidelity than is possible with processes based on adiabatic transport.

arXiv:0803.0183Physical Review AMay 28, 200870 citations

Controlling atomic states by optical pulses

K. Igeta, Bernd Hüttner, Nobuyuki Imoto

Aug 24, 20050 citations

We demonstrate quantum control techniques for a single trapped ion in a cryogenic, surface-electrode trap. A narrow optical transition of

{\mathrm{Sr}}^{+}

along with the ground and first excited motional states of the harmonic trapping potential form a two-qubit system. The optical qubit transition is susceptible to magnetic field fluctuations, which we stabilize with a simple and compact method using superconducting rings. Decoherence of the motional qubit is suppressed by the cryogenic environment. ac Stark shift correction is accomplished by controlling the laser phase in the pulse sequencer, eliminating the need for an additional laser. Quantum process tomography is implemented on atomic and motional states by use of conditional pulse sequences. With these techniques, we demonstrate a Cirac-Zoller controlled-not gate in a single ion with a mean fidelity of

91(1)%