D J. Berkeland

Sum-frequency generation of continuous-wave light at 194 nm

Over 2 mW of continuous-wave tunable 194-nm light is produced by sum-frequency mixing approximately 500 mW of 792-nm and 500 mW of 257-nm radiation in beta-barium borate (BBO). The powers in both fundamental beams are enhanced in separate ring cavities whose optical paths overlap in the Brewster-cut BBO crystal. Due to the higher circulating fundamental powers, the sum-frequency-generated power is nearly 2 orders of magnitude greater than previously reported values.

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.

Lasers for an optical frequency standard using trapped Hg+ ions

We are developing an optical frequency standard based on the narrow 281.5 nm transition of trapped lg9Hgt ions. A major step toward the completion of this standard is the construction of an isolated high-finesse Fabry-PCrot cavity to stabilize the local oscillator. The cavity system that we have assembled has enabled the creation of an optical frequency source with good short-term stability. Eventually, this frequency source will derive long-term stability from a lock to the Hgt transition. We have recently demonstrated an improved linewidth of 0.6 Hz (40 s averaging time) for a 563 nm dye laser locked to our stable cavity. Additionally, we are developing solid-state laser replacements for gas and dye lasers presently used for driving 194 nm and 281.5 nm Hgt transitions.

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.

Lasers for a trapped Hg/sup +/ optical frequency standard

We have demonstrated a frequency source at 563 nm with an approximately 6 Hz linewidth for use in an optical frequency standard based on trapped and cooled /sup 199/Hg/sup +/ ions. Additionally, we are developing solid state laser replacements for gas and dye lasers presently used for driving 194 nm and 282 nm /sup 199/Hg/sup +/ transitions.

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.