D. M. Meekhof

Experimental Issues in Coherent Quantum-State Manipulation of Trapped Atomic Ions.

Methods for, and limitations to, the generation of entangled states of trapped atomic ions are examined. As much as possible, state manipulations are described in terms of quantum logic operations since the conditional dynamics implicit in quantum logic is central to the creation of entanglement. Keeping with current interest, some experimental issues in the proposal for trappedion quantum computation by J. I. Cirac and P. Zoller (University of Innsbruck) are discussed. Several possible decoherence mechanisms are examined and what may be the more important of these are identified. Some potential applications for entangled states of trapped-ions which lie outside the immediate realm of quantum computation are also discussed.

Heating of trapped ions from the quantum ground state

We have investigated motional heating of laser-cooled

Simplified quantum logic with trapped ions

{}^{9}{\mathrm{Be}}^{+}

Experimental preparation and measurement of quantum states of motion of a trapped atom

ions held in radio-frequency (Paul) traps. We have measured heating rates in a variety of traps with different geometries, electrode materials, and characteristic sizes. The results show that heating is due to electric-field noise from the trap electrodes that exerts a stochastic fluctuating force on the ion. The scaling of the heating rate with trap size is much stronger than that expected from a spatially uniform noise source on the electrodes (such as Johnson noise from external circuits), indicating that a microscopic uncorrelated noise source on the electrodes (such as fluctuating patch-potential fields) is a more likely candidate for the source of heating.

Experimental Primer on the Trapped Ion Quantum Computer

Abstract : We describe a simplified scheme for quantum logic with a collection of laser-cooled trapped atomic ions. Building on the scheme of Cirac and Zoller, we show how the fundamental controlled-NOT gate between a collective mode of ion motion and the internal states of a single ion can be reduced to a single laser pulse, and the need for a third auxiliary internal electronic state can be eliminated.

Quantum state manipulation of trapped atomic ions

Abstract We report the creation and full determination of several quantum states of motion of a 9Be+ ion bound in a RF (Paul) trap. The states are coherently prepared from an ion which has been initially laser cooled to the zero-point of motion. We create states having both classical and non-classical character including thermal, number, coherent, squeezed, and ‚Schrodinger cat‘ states. The motional quantum state is fully reconstructed using two novel schemes that determine the density matrix in the number state basis or the Wigner function. Our techniques allow well controlled experiments decoherence and related phenomena on the quantum-classical borderline.

Accuracy evaluation of a cesium fountain primary frequency standard at NIST

The development of a quantum computer based on a system of trapped atomic ions is described, following the proposal of Cirac and Zoller. Initial results on a two-bit quantum logic gate are presented, and select experimental issues in scaling the system to larger numbers of ions and gates are treated.

Primary Atomic Frequency Standards at NIST

A single laser–cooled and trapped 9Be+ ion is used to investigate methods of coherent quantum–state synthesis and quantum logic. We create and characterize non–classical states of motion including ‘Schrodinger–cat’ states. A fundamental quantum logic gate is realized which uses two states of the quantized ion motion and two ion internal states as qubits. We explore some of the applications for, and problems in realizing, quantum computation based on multiple trapped ions.

Quantum Harmonic Oscillator State Synthesis and Analysis

Since November of 1998, we have performed five frequency uncertainty evaluations on NIST F-1, our laser-cooled cesium fountain. The results from the latest evaluation have a statistical uncertainty of 1.4/spl times/10/sup -15/ and an uncorrected bias of 0.7/spl times/10/sup -15/. The results have been reported to the BIPM for inclusion in TAI, making this clock one of two cesium fountain clocks used as primary standards in the world. We will present an overview of the evaluations and their uncertainties.

Accuracy results from NIST-F1 laser-cooled cesium primary frequency standard

The development of atomic frequency standards at NIST is discussed and three of the key frequency-standard technologies of the current era are described. For each of these technologies, the most recent NIST implementation of the particular type of standard is described in greater detail. The best relative standard uncertainty achieved to date for a NIST frequency standard is 1.5×10−15. The uncertainties of the most recent NIST standards are displayed relative to the uncertainties of atomic frequency standards of several other countries.