Showing papers by "B. E. King published in 1996"

A "Schrodinger Cat" Superposition State of an Atom

Abstract: A "Schrodinger cat"-like state of matter was generated at the single atom level. A trapped 9Be+ ion was laser-cooled to the zero-point energy and then prepared in a superposition of spatially separated coherent harmonic oscillator states. This state was created by application of a sequence of laser pulses, which entangles internal (electronic) and external (motional) states of the ion. The Schrodinger cat superposition was verified by detection of the quantum mechanical interference between the localized wave packets. This mesoscopic system may provide insight into the fuzzy boundary between the classical and quantum worlds by allowing controlled studies of quantum measurement and quantum decoherence.

Generation of nonclassical motional states of a trapped atom.

Abstract: We report the creation of thermal, Fock, coherent, and squeezed states of motion of a harmonically bound {sup 9}Be{sup +} ion. The last three states are coherently prepared from an ion which has been initially laser cooled to the zero point of motion. The ion is trapped in the regime where the coupling between its motional and internal states, due to applied (classical) radiation, can be described by a Jaynes-Cummings-type interaction. With this coupling, the evolution of the internal atomic state provides a signature of the number state distribution of the motion. {copyright} {ital 1996 The American Physical Society.}

Generation of Non-classical Motional States of a Trapped Atom

Abstract: We report the creation of thermal, Fock, coherent, and squeezed states of motion of a harmonically bound {sup 9}Be{sup +} ion. The last three states are coherently prepared from an ion which has been initially laser cooled to the zero point of motion. The ion is trapped in the regime where the coupling between its motional and internal states, due to applied (classical) radiation, can be described by a Jaynes-Cummings-type interaction. With this coupling, the evolution of the internal atomic state provides a signature of the number state distribution of the motion. {copyright} {ital 1996 The American Physical Society.}

Experimental Determination of the Motional Quantum State of a Trapped Atom

Abstract: We reconstruct the density matrices and Wigner functions for various quantum states of motion of a harmonically bound ${}^{9}{\mathrm{Be}}^{+}$ ion. We apply coherent displacements of different amplitudes and phases to the input state and measure the number state populations. Using novel reconstruction schemes we independently determine both the density matrix in the number state basis and the Wigner function. These reconstructions are sensitive indicators of decoherence in the system.

Application of Laser-Cooled Ions to Frequency Standards and Metrology

Abstract: With the first experiments on laser cooling, it was realized that a principal application of the technique would be to reduce Doppler shifts in freqwncy stand9tds. Loser cooling is still thought to be eaxntid to achieve uncertainty significantly smaller than 1 part in io"; however, a number of other problems must be solved to achieve this goal with stored atomic ions. For both RF/microwave and optical frequency standards based on trapped ions, some of theae problems are discussed. Laser cooling of trapped ions also appears to be important for other reasons in metrology. For example, for frequency standards, cooling to the zero-point of motion should enable the creation of quantum mechanically correlated statas for improved signal-to-noise ratio in spectroscopy, or provide accurate " e n t of Stark shifts. cooling to the zero-point of motion also enables the creation of nonclassical states of motion or correlated states which may be applicable to sensitive detection, quautum computation, or to test quantum " e n t principles. Techniques to achieve laser cooling to the zero-point of motion are briefly described.

Manipulating the Motion of a Single Trapped Atom

Abstract: A single atom confined in an electromagnetic trap (see Figure 1) has many similarities to a molecule. Spectroscopy reveals both internal electronic structure and external vibrational structure. In the case of a trapped atom, the vibrational states can be controlled to a high degree, primarily because the effective vibrational potential is externally applied and can be made almost purely harmonic. By coupling the electronic and vibrational states of a trapped atom with laser radiation, motional wavepackets of the atom can be manipulated and interesting states of motion can be created which exhibit highly nonclassical behavior. In this Account, we describe experiments which control the bound states of a “molecule” formed by a single trapped atomic ion bound to a harmonic trap. We create1 (i) Fock states (eigenstates of vibration) including the n ) 0 zero-point vibrational ground state, (ii) coherent states, where the wavepacket orbit corresponds most closely to classical oscillation in the trap, (iii) squeezed states, in which the wavepackets undergo a “breathing” mode in the trap, and (iv) “Schrodinger cat” states of motion,2 where the trapped ion is placed in a coherent superposition of spatially separated coherent states. Such states of motion are useful for a number of applications, including issues involving quantum measurement theory, sensitive electronic detection,3 spectroscopy below the quantum

Entangled States of Atomic Ions for Quantum Metrology and Computation

Abstract: A single trapped ’Be’ ion is used to investigate Japes4hmhgs dynamics for a two-level system coupled to harmonic atomic motion We create md invtstigate nonclassicll states of motion including “Schr&Iinger-sat” dates. A rundamental quantum logic gate is realized using the quantized motion and internal dates as qubits. We explore acme of the app1icat.i~ for, and problems in realizing, quantum logic bascd on multiple trapped ions.

Nonclassical motional states of a trapped atom

Abstract: Summary form only given. We report the creation of thermal, Fock, coherent, squeezed, and Schrodinger cat states of motion of a single /sup 9/Be/sup +/ atomic ion that is confined in a Paul-rf trap. The thermal state of motion is created by Doppler cooling on the 313 nm transition. The other states are coherently prepared from an ion that has first been placed in the zero-point motional state through resolved sideband laser cooling by use of stimulated Raman transitions.