Time has always had a special status in physics because of its fundamental role specifying the regularities nature and extraordinary precision with which it can be measured. This enables tests cosmology, as well practical applications such satellite navigation. Recently, regime operation for atomic clocks based on optical transitions become possible, promising even higher performance. We report frequency ratio two fractional uncertainty 5.2 × 10 –17 . The aluminum mercury single-ion clock...

Bose-Einstein condensates of sodium atoms have been prepared in optical and magnetic traps which the energy-level spacing one or two dimensions exceeds interaction energy between atoms, realizing lower dimensionality. The crossover into two-dimensional one-dimensional was observed by a change aspect ratio release converging to nonzero value when number trapped reduced.

We have constructed an optical clock with a fractional frequency inaccuracy of 8.6x10{-18}, based on quantum logic spectroscopy Al+ ion. A simultaneously trapped Mg+ ion serves to sympathetically laser cool the and detect its state. The {1}S{0}<-->{3}P{0} transition is compared that previously statistical measurement uncertainty 7.0x10{-18}. two clocks exhibit relative stability 2.8x10{-15}tau{-1/2}, difference -1.8x10{-17}, consistent accuracy limit older clock.

Observers in relative motion or at different gravitational potentials measure disparate clock rates. These predictions of relativity have previously been observed with atomic clocks high velocities and large changes elevation. We time dilation from speeds less than 10 meters per second by comparing two optical connected a 75-meter length fiber. can now also detect due to change height near Earth's surface 1 meter. This technique may be extended the field geodesy, applications geophysics...

We present a general technique for precision spectroscopy of atoms that lack suitable transitions efficient laser cooling, internal state preparation, and detection. In our implementation with trapped atomic ions, an auxiliary "logic" ion provides sympathetic initialization, detection simultaneously "spectroscopy" ion. Detection is achieved by applying mapping operation to each ion, which results in coherent transfer the ion's onto logic where it then measured high efficiency. Experimental...

We demonstrate experimentally a robust quantum memory using magnetic-field-independent hyperfine transition in 9Be+ atomic ion qubits at magnetic field B approximately = 0.01194 T. observe that the single physical qubit coherence time is greater than 10 s, an improvement of 5 orders magnitude from previous experiments with 9Be+. also long times decoherence-free subspace logical comprising two entangled and discuss merits each type qubit.

Chemical reactions typically proceed via stochastic encounters between reactants. Going beyond this paradigm, we combine exactly two atoms into a single, controlled reaction. The experimental apparatus traps individual laser-cooled (one sodium and one cesium) in separate optical tweezers then merges them dipole trap. Subsequently, photoassociation forms an excited-state NaCs molecule. discovery of previously unseen resonances near the molecular dissociation threshold measurement collision...

Femtochemistry techniques have been instrumental in accessing the short time scales necessary to probe transient intermediates chemical reactions. Here we take contrasting approach of prolonging lifetime an intermediate by preparing reactant molecules their lowest ro-vibronic quantum state at ultralow temperatures, thereby drastically reducing number exit channels accessible upon mutual collision. Using ionization spectroscopy and velocity-map imaging a trapped gas potassium-rubidium...

We have observed phase singularities due to vortex excitation in Bose-Einstein condensates. Vortices were created by moving a laser beam through condensate. They as dislocations the interference fringes formed stirred condensate and second unperturbed The velocity dependence for time scale re-establishing uniform across determined.

We report, for the first time, laser spectroscopy of 1S0-->3P0 clock transition in 27Al+. A single aluminum ion and a beryllium are simultaneously confined linear Paul trap, coupled by their mutual Coulomb repulsion. This coupling allows to sympathetically cool also enables transfer aluminum's electronic state beryllium's hyperfine state, which can be measured with high fidelity. These techniques applied measure frequency nu=1,121,015,393,207,851(6) Hz. They used lifetime metastable...

We have investigated ion dynamics associated with a dual linear trap where ions can be stored in and moved between two distinct locations. Such is building block for system to engineer arbitrary quantum states of ensembles. Specifically, this the unit cell strategy scalable computing using series interconnected traps. transferred an locations 1.2 mm apart 50 µs near efficiency (> 106 consecutive transfers) negligible motional heating, while maintaining internal-state coherence. In addition,...

Using two trapped ion species ((27)Al(+) and (9)Be(+)) as primary ancillary quantum systems, we implement qubit measurements based on the repetitive transfer of information nondemolition detection. The repetition provides a natural mechanism for an adaptive measurement strategy, which leads to exponentially lower error rates compared using fixed number detection cycles. For single demonstrate 99.94% fidelity. We also technique adaptively measuring multiple states ancilla, apply spectroscopy...

Proposed molecular quantum gate takes advantage of internal coherence and resonant electric dipolar interaction with high fidelity optical scalability.

We demonstrate the cooling of a two species ion crystal consisting one $^9Be^+$ and $^{24}Mg^+$ ion. Since respective transitions these are separated by more than 30 nm, laser manipulation has negligible effect on other even when ions not individually addressed. As such this is useful system for re-initializing motional state in an trap quantum computer without affecting qubit information. Additionally, we have found that mass difference between enables novel method detecting subsequently...

Experiments directed towards the development of a quantum computer based on trapped atomic ions are described briefly. We discuss implementation single-qubit operations and gates between qubits. A geometric phase gate two ion qubits is described. Limitations trapped-ion method such as those caused by Stark shifts spontaneous emission addressed. Finally, we describe strategy to realize large-scale device.

We show how an experimentally realized set of operations on a single trapped ion is sufficient to simulate wide class Hamiltonians spin-1/2 particle in external potential. This system also able other physical dynamics. As demonstration, we the action two nth order nonlinear optical beam splitters comprising interferometer sensitive phase shift one paths. The sensitivity determining these shifts increases linearly with n, and simulation demonstrates that use (n=2,3) enhances this compared...

We present an optical cavity design that is insensitive to both vibrations and orientation. The based on a spherical spacer held rigidly at two points diameter of the sphere. Coupling support forces length reduced by holding sphere "squeeze angle" with respect axis. Finite element analysis used calculate acceleration sensitivity for ideal geometry as well several varieties fabrication errors. measured initial, sub-ideal version mounted 4.0(5)×10(-11)/g, 1.6(3)×10(-10)/g, 3.1(1)×10(-10)/g...

We have investigated ion dynamics associated with a dual linear trap where ions can be stored in and moved between two distinct locations. Such is building block for system to engineer arbitrary quantum states of ensembles. Specifically, this the unit cell strategy scalable computing using series interconnected traps. transferred an locations 1.2 mm apart 50 $\mu$s near efficiency ($&gt; 10^{6}$ consecutive transfers) negligible motional heating, while maintaining internal-state coherence....

The coherence of a hyperfine-state superposition trapped 9Be+ ion in the presence off-resonant light is studied experimentally. It shown that Rayleigh elastic scattering photons does not change state populations also affect coherence. We observe times exceed average time 19 which determined from measured Stark shifts. This result implies that, with sufficient control over its parameters, laser can be used to manipulate superpositions very little decoherence.

We have investigated theoretically and experimentally a method for preparing Dicke states in trapped atomic ions. consider linear chain of $N$ ion qubits that is prepared particular Fock state motion $|m⟩$. The $m$ phonons are removed by applying laser pulse globally to the converting motional excitation flipped spins. global nature this ensures spins shared all target ions close approximation $|{D}_{N}^{(m)}⟩$. calculate numerically fidelity limits protocol find small deviations from ideal...

We place two atoms in quantum superposition states and observe coherent phase evolution for 3.4x10^15 cycles. Correlation signals from the yield information about their relative even after probe radiation has decohered. This technique was applied to a frequency comparison of Al+ ions, where fractional uncertainty 3.7+1.0-0.8x10^-16/\sqrt{\tau/s} observed. Two measures Q-factor are reported: The derived coherence is 3.4+2.4-1.1x10^16, spectroscopic Ramsey time 3 s 6.7x10^15. As part this...

We characterize the frequency sensitivity of a cavity-stabilized laser to inertial forces and temperature fluctuations, perform real-time feedforward correct for these sources noise. measure cavity linear accelerations, rotational velocities by rotating it about three axes with accelerometers gyroscopes positioned around cavity. The worst-direction acceleration is $2(1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ g${}^{\ensuremath{-}1}$ measured over 0--50 Hz, which reduced...