J D. Miller

Quantum state manipulation of trapped atomic ions

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.

High-resolution, high-accuracy spectroscopy of trapped ions

Microwave spectroscopy using trapped and cooled ions can achieve precision and accuracy comparable to the best cesium frequency standards. We discuss standards based on {sup 199}Hg{sup +} ions trapped in linear Paul traps: the Jet Propulsion Laboratory (JPL) standard, which uses up to 10{sup 7} atoms confined near the trap axis, and the recently evaluated NIST standard, which uses approximately ten ions laser cooled and crystalized on the trap axis. We consider future directions in trapped ion frequency standard work, including the use of entangled states for achieving higher precision, and progress on trapped ion optical frequency standards. Finally, we discuss scientific and technical applications of extremely stable frequency standards.

High-performance trapped Hg/sup +/ frequency standards

We have demonstrated a new frequency standard, accurate to 3.4/spl times/10/sup -15/, based on the 40.5 GHz ground state hyperfine transition in cooled and trapped /sup 199/Hg/sup +/. We are also developing an optical frequency standard based on /sup 199/Hg/sup +/. The spectral width of the 563 nm laser used in this standard is less than 6 Hz.

Coherent Quantum State Manipulation of Trapped Atomic Ions

Abstract A single, laser-cooled, trapped 9 Be + ion is used to investigate methods of coherent quantum-state synthesis. We create and characterize nonclassical states of motion including “Schrodinger-cat” states. A fundamental quantum logic gate is realized using the quantized motion and internal states as qubits. We explore some of the applications for, and problems in realizing, quantum computation based on multiple trapped ions.

A cryogenic linear ion trap for /sup 199/Hg/sup +/ frequency standards

A cryogenic linear rf trap has been constructed to study the accuracy of a clock based on laser cooled /sup 199/Hg/sup +/. Crystals of tens of ions have been observed. The residual micromotion of the ions has been minimized and Ramsey interrogation periods of 100 s have been demonstrated for the 40.5 GHz transition. Systematic shifts to the clock transition due to magnetic field fluctuations as well as heating of the ions during the clock cycle have been evaluated. This system should eventually provide a frequency standard of high precision and accuracy.