A5016429316- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Frequency and Time Standards
- Quantum Information and Cryptography
- Atomic and Subatomic Physics Research
- Quantum optics and atomic interactions
- Quantum Mechanics and Applications
- Particle physics theoretical and experimental studies
- Quantum Computing Algorithms and Architecture
- Quantum Chromodynamics and Particle Interactions
- Scientific Measurement and Uncertainty Evaluation
- Atomic and Molecular Physics
- Nuclear physics research studies
- Radioactive Decay and Measurement Techniques
- High-Energy Particle Collisions Research
- Spectroscopy and Quantum Chemical Studies
- Superconducting Materials and Applications
- Medical Imaging Techniques and Applications
- Advanced Thermodynamics and Statistical Mechanics
- Spectroscopy Techniques in Biomedical and Chemical Research
- Hemodynamic Monitoring and Therapy
- Computational Physics and Python Applications
- Laser-Matter Interactions and Applications
- Advanced Fiber Laser Technologies
- Quantum, superfluid, helium dynamics
- Spectroscopy and Laser Applications
National University of Singapore
2013-2024
Centre for Quantum Technologies
2013-2024
National Metrology Center
2024
National Metrology Centre
2023-2024
National Institute of Standards and Technology
2003-2015
University of Colorado Boulder
2015
Campbell Collaboration
2009
Institute of Physics Belgrade
2005
University of Birmingham
2005
University of Otago
1996-2005
The pursuit of better atomic clocks has advanced many research areas, providing quantum state control, new insights in science, tighter limits on fundamental constant variation, and improved tests relativity. record for the best stability accuracy is currently held by optical lattice clocks. This work takes an important step towards realizing full potential a many-particle clock with state-of-the-art stable laser. Our 87Sr now achieves fractional 2.2e-16 at 1 s. With this stability, we...
The precision in spectroscopy of any quantum system is fundamentally limited by the Heisenberg uncertainty relation for energy and time. For N systems, this limit requires that they be a quantum-mechanically entangled state. We describe scalable method can potentially take full advantage entanglement to reach has practical spectroscopic information transferred states with optimal protection against readout noise. demonstrate our experimentally three beryllium ions. sensitivity attained...
We have created a Bose-Einstein condensate (BEC) of ${}^{87}\mathrm{Rb}$ atoms directly in an optical trap. employ quasielectrostatic dipole force trap formed by two crossed ${\mathrm{CO}}_{2}$ laser beams. Loading from sub-Doppler laser-cooled cloud results initial phase space densities $\ensuremath{\sim}1/200$. Evaporatively cooling through the BEC transition is achieved lowering power trapping beams over $\ensuremath{\sim}2\mathrm{s}$. The resulting condensates are...
We measure spin mixing of $F=1$ and $F=2$ spinor condensates $^{87}\mathrm{Rb}$ atoms confined in an optical trap. determine the time to be typically less than 600 ms observe population oscillations. The equilibrium configuration manifold is measured for different magnetic fields found show ferromagnetic behavior low field gradients. An condensate created by microwave excitation from manifold, this spin-2 observed decay exponentially with constant 250 ms. Despite short lifetime within 50
We realize an open version of the Dicke model by coupling two hyperfine ground states using cavity-assisted Raman transitions. The interaction due to only one couplings is described Tavis-Cummings and we observe a normal mode splitting in transmission around dispersively shifted cavity. With both present dynamics are measure onset superradiant scattering into cavity above critical strength.
We realize a spin-1 Dicke model using magnetic sub-levels of the lowest F=1 hyperfine level $^{87}$Rb atoms confined to high finesse cavity. study this system under conditions imbalanced driving, which is predicted have rich phase diagram nonequilibrium phases and transitions. observe both super-radiant oscillatory from cavity output spectra as by theory. Exploring over wide range parameters, we obtain boundaries between normal, phases, compare with theoretical model.
The extreme precision of optical atomic clocks has led to an anticipated redefinition the second by International System Units. Furthermore, accuracies pushing boundary 1 part in 1018 and beyond will enable new applications, such as geodesy tests fundamental physics. 1S0 3D1 transition 176Lu+ exceptionally low sensitivity external perturbations, making it suitable for practical clock implementations with inaccuracy at or below 10-18. Here, we perform high-accuracy comparisons between two...
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 report the implementation of semiclassical quantum Fourier transform in a system three beryllium ion qubits (two-level systems) confined segmented multizone trap. The is crucial final step Shor's algorithm, and it acts on register to determine periodicity state's amplitudes. Because only probability amplitudes are required for this task, more efficient version can be used, which single-qubit operations conditioned measurement outcomes required. apply several input states different...
We have demonstrated a storage ring for ultracold neutral atoms. Atoms with mean velocities of 1 m/s corresponding to kinetic energies $\ensuremath{\sim}100\mathrm{neV}$ are confined 2 cm diameter by magnetic forces produced two current-carrying wires. Up ${10}^{6}$ atoms loaded at time in the ring, and seven revolutions clearly observed. Additionally, we multiple loading deterministic manipulation longitudinal velocity distribution using applied laser pulses. Applications this include large...
We report the implementation of quantum dense coding on individual atomic qubits with use two trapped 9Be+ ions. The protocol is implemented a complete Bell measurement that distinguishes four operations used to encode bits classical information. measure an average transmission fidelity 0.85(1) and determine channel capacity 1.16(1).
The Dicke model is of fundamental importance in quantum mechanics for understanding the collective behavior atoms coupled to a single electromagnetic mode. Here, we demonstrate Dicke-model simulation via cavity-assisted Raman transitions configuration using counterpropagating laser beams. observations indicate that motional effects should be included fully account results. These results are contrary experiments single-beam and copropagating configurations. We give theoretical description...
We propose a method for engineering spin dynamics in ensembles of integer-spin atoms confined within high-finesse optical cavity. Our proposal uses cavity-assisted Raman transitions to engineer Dicke model atoms, which, dispersive limit, reduces effective atom-atom interactions the ensemble. This scheme offers promising and flexible new avenue exploration wide range spinor many-body physics. As an example this, we present results showing that this can be used generate spin-nematic squeezing...
We make a detailed experimental study of the threshold for self-organization thermal $^{87}\mathrm{Rb}$ atoms coupled to high-finesse cavity over range atom numbers and detunings. investigate difference between probing with traveling wave retroreflected lattice. These two scenarios lead qualitatively different behavior in terms response system as function detuning respect probe. In both cases, we confirm ${N}^{\ensuremath{-}1}$ scaling number.
The accuracy of state-of-the-art atomic clocks is derived from the insensitivity narrow optical resonances to environmental perturbations. Two such in singly ionized lutetium have been identified with potentially lower sensitivities compared other clock candidates. Here we report measurement most significant unknown property both transitions, static differential scalar polarizability. From this, fractional blackbody radiation shift for one transitions found be -1.36(9) × 10-18 at 300 K,...
We investigate the feasibility of precision frequency metrology with large ion crystals. For clock candidates a negative differential static polarizability, we show that micromotion effects should not impede performance clock. Using ${\mathrm{Lu}}^{+}$ as specific example, quadrupole shifts due to electric fields from neighboring ions do significantly affect performance. also tensor polarizability can be effectively managed compensation laser at least for small number...
We report the first measurement of $D^{\ast -}$ meson polarization in decay $B^0 \to D^{*-} \tau^+\nu_{\tau}$ using full data sample 772$\times 10^6$ $B\bar{B}$ pairs recorded with Belle detector at KEKB electron-positron collider. Our result, $F_L^{D^\ast} = 0.60 \pm 0.08 ({\rm stat}) 0.04 sys})$, where $F_L^{D^\ast}$ denotes $D^{\ast-}$ longitudinal fraction, agrees within about $1.7$ standard deviations model prediction.
Abstract We present a numerical method for extrapolating polarizability measurements to dc as done in the assessment of blackbody radiation shifts ion-based clocks. The explicitly accounts frequency dependence relevant atomic transitions without introducing an ad hoc modelling function. It incorporates priori structure calculations, which allows be augmented by calculations if there is insufficient data make purely measurement based estimate. also provides indicators inconsistencies between...
We report an absolute frequency measurement of the $^{1}\rm S_0$ to $^{3}\rm D_1$ optical clock transition in $^{176}{\rm Lu}^{+}$. Traceability International System Units (SI) is realized by remote link Atomic Time. The result $353\,638\,794\,073\,800.34(32)$Hz, a fractional uncertainty $9.1 \times 10^{-16}$. was obtained operating single-ion Lu}^{+}$ standard intermittently over 3 months with total uptime 162 hours. This first reported value for ${\rm Lu}^{+}\,(^{3}\rm D_1)$ standard.
We examine a range of effects arising from ac magnetic fields in high-precision metrology. These results are directly relevant to measurements and accuracy assessments for state-of-the-art optical clocks. Strategies characterize these discussed simple technique accurately determine trap-induced linear Paul trap is demonstrated by using $^{171}\mathrm{Yb}^{+}$.
We examine the validity of harmonic approximation, where radio-frequency ion trap is treated as a trap, in problem regarding controlled collision trapped atom and single ion. This equivalent to studying effect micromotion since this motion must be neglected for considered oscillator. By applying transformation Cook Shankland we find that can represented by two periodically oscillating operators. In order investigate on dynamics atom-ion system, calculate (i) coupling strengths operators...