Quantum States of Motion

Ben Q. Baragiola, Jason Twamley

Nonclassical motional states of matter are of interest both from a fundamental perspective but also for their potential technological applications as resources in various quantum processing tasks such as quantum teleportation, sensing, communication, and computation. In this work we explore the motional effects of a harmonically trapped, excited two-level emitter coupled to a one-dimensional photonic system. As the emitter decays it experiences a momentum recoil that entangles its motion with the emitted photon pulse. In the long-time limit the emitter relaxes to its electronic ground state, while its reduced motional state remains entangled with the outgoing photon. We find photonic systems where the long-time reduced motional state of the emitter, though mixed, is highly nonclassical and in some cases approaches a pure motional Fock state. Motional recoil engineering can be simpler to experimentally implement than complex measurement and feedback based methods to engineer novel quantum mechanical states of motion.

David F. P. Pile

Daniel M. Greenberger

Liu Tang

The fidelities of quantum states of system in Jaynes Cummings model containing atomic motion under action of coherent field are studied. The influence of atomic motion and the field mode structure on the fidelities of quantum states of system in different atomic initial states is discussed. The result indicates that both the atomic motion and the field mode structure can modulate the fidelities of quantum states in the system of interaction.

Ferdinand Schmidt‐Kaler, Hartmut Häffner, S. Gulde +5 more

A single 40 Ca + -ion is trapped and laser-cooled to its motional ground state. Laser radiation which couples off-resonantly to a motional sideband of the ion's S 1/2 to D 5/2 transition causes a phase shift proportional to the ion's motional quantum state | n ⟩. As the phase shift is conditional upon the ion's motion, we are able to demonstrate a universal 2-qubit quantum gate operation where the electronic target state { S , D } is flipped depending on the motional qubit state | n ⟩ = {|0⟩,|1⟩}. Finally, we discuss scaling properties of this universal quantum gate for linear ion crystals and present numerical simulations for the generation of a maximally entangled state of five ions.

Gerald Teschl