A5067780091- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Advanced Frequency and Time Standards
- Spectroscopy and Laser Applications
- Atomic and Molecular Physics
- Quantum optics and atomic interactions
- Quantum Information and Cryptography
- Mechanical and Optical Resonators
- Advanced Chemical Physics Studies
- Quantum, superfluid, helium dynamics
- Laser Design and Applications
- Molecular Spectroscopy and Structure
- Advanced Fiber Laser Technologies
- Laser-Matter Interactions and Applications
- Quantum Electrodynamics and Casimir Effect
- Experimental and Theoretical Physics Studies
- Laser-induced spectroscopy and plasma
- Spectroscopy and Quantum Chemical Studies
- Inorganic Fluorides and Related Compounds
- Optical properties and cooling technologies in crystalline materials
- Atmospheric Ozone and Climate
- Radioactive Decay and Measurement Techniques
- Magnetic confinement fusion research
- Orbital Angular Momentum in Optics
- Dark Matter and Cosmic Phenomena
Imperial College London
2015-2024
University of Oxford
1999-2007
University of Sussex
2002
The most sensitive measurements of the electron electric dipole moment ${d}_{e}$ have previously been made using heavy atoms. Heavy polar molecules offer a greater sensitivity to because interaction energy be measured is typically ${10}^{3}$ times larger than in atom. We used YbF make first measurement this kind. Together, large and strong tensor polarizability molecule our experiment essentially free systematic errors that currently limit Our result...
We demonstrate slowing and longitudinal cooling of a supersonic beam CaF molecules using counter-propagating laser light resonant with closed rotational almost vibrational transition. A group are decelerated by about 20 m/s applying fixed frequency for 1.8 ms. Their velocity spread is reduced, corresponding to final temperature 300 mK. The further reduced chirping the keep it in resonance as slow down.
We demonstrate one-dimensional sub-Doppler laser cooling of a beam YbF molecules to 100 μK. This is key step towards measurement the electron's electric dipole moment using ultracold molecules. compare effectiveness magnetically assisted and polarization-gradient mechanisms. model experiment find good agreement with our data.
We have decelerated a supersonic beam of $^{174}\mathrm{YbF}$ molecules using switched sequence electrostatic field gradients. These are 7 times heavier than any previously decelerated. An alternating gradient structure allows us to decelerate and focus the in their ground state. show that decelerator exhibits axial transverse stability required bring rest. Our work significantly extends range amenable this powerful method cooling trapping.
We demonstrate a scheme for magneto-optically trapping strontium monofluoride (SrF) molecules at temperatures one order of magnitude lower and phase space densities 3 orders higher than obtained previously with laser-cooled molecules. In our trap, optical dark states are destabilized by rapidly synchronously reversing the laser polarizations applied magnetic field gradient. The number trap lifetime also significantly improved from previous work loading high power then reducing long-term...
We explore the uses of ultracold molecules as a platform for future experiments in field quantum simulation, focusing on two molecular species, $^{40}$Ca$^{19}$F and $^{87}$Rb$^{133}$Cs. report development coherent state control using microwave fields both species; this is crucial ingredient many simulation applications. demonstrate proof-of-principle Ramsey interferometry measurements with fringe spacings $\sim 1~\rm kHz$ investigate dephasing time superposition $N=0$ $N=1$ rotational...
We discuss how the internal structure of ultracold molecules, trapped in motional ground state optical tweezers, can be used to implement qudits. explore rotational, fine and hyperfine $^{40}$Ca$^{19}$F $^{87}$Rb$^{133}$Cs, which are examples molecules with $^2\Sigma$ $^1\Sigma$ electronic states, respectively. In each case we identify a subset levels within single rotational manifold suitable 4-level qudit. Quantum gates implemented using two-photon microwave transitions via neighboring...
We recently reported a new measurement of the electron's electric dipole moment using YbF molecules (Hudson et al 2011 Nature 473 493). Here, we give more detailed description methods used to make this measurement, along with fuller analysis data. show how our isolate from imperfections in experiment that might mimic it. describe systematic errors discovered, and small corrections made account for these. By making set additional measurements greatly exaggerated experimental imperfections,...
We demonstrate coherent microwave control of the rotational, hyperfine, and Zeeman states ultracold CaF molecules, magnetic trapping these molecules in a single, selectable quantum state. trap about $5\ifmmode\times\else\texttimes\fi{}{10}^{3}$ for almost 2 s at temperature $70(8)\text{ }\text{ }\ensuremath{\mu}\mathrm{K}$ density $1.2\ifmmode\times\else\texttimes\fi{}{10}^{5}\text{ }{\mathrm{cm}}^{\ensuremath{-}3}$. measure state-specific loss rate due to collisions with background helium.
We propose an experiment to measure the electric dipole moment (EDM) of electron using ultracold YbF molecules. The molecules are produced as a thermal beam by cryogenic buffer gas source, and brought rest in optical molasses that cools them Doppler limit or below. molecular cloud is then thrown upward form fountain which EDM measured. A non-zero result would be unambiguous proof new elementary particle interactions, beyond standard model.
We introduce a scheme for deep laser cooling of molecules based on robust dark states at zero velocity. By simulating this scheme, we show it to be widely applicable method that can reach the recoil limit or below. demonstrate and characterize experimentally, reaching temperature 5.4(7) μK. solve general problem measuring low temperatures large clouds by rotating phase-space distribution then directly imaging complete velocity distribution. Using same rotation method, rapidly compress cloud....
Polar molecules are an emerging platform for quantum technologies based on their long-range electric dipole--dipole interactions, which open new possibilities information processing and the simulation of strongly correlated systems. Here, we use magnetic microwave fields to design a fast entangling gate with $>0.999$ fidelity is robust respect fluctuations in trapping control small thermal excitations. These results establish feasibility build scalable processor broad range molecular species...
Many modern theories predict that the fundamental constants depend on time, position, or local density of matter. We develop a spectroscopic method for pulsed beams cold molecules, and use it to measure frequencies microwave transitions in CH with accuracy down 3 Hz. By comparing these those measured from sources Milky Way, we test hypothesis may differ between high low environments Earth interstellar medium. For fine structure constant find \Delta\alpha/\alpha = (0.3 +/- 1.1)*10^{-7},...
Laser cooling and magneto-optical trapping of molecules typically involves multiple transitions driven by several laser frequencies. We analyze how forces depend on the angular momenta, $F_l$ $F_u$, g-factors, $g_l$ $g_u$, lower upper states. When $F_l > F_u$ polarizations must be reversed relative to cases where $F_u \ge F_l$. The correct choice circular polarization depends sign $g_{u}$ but not $g_{l}$. If is zero there no force, force very weak whenever $g_u$ small compared $g_l$, which...
We prepare mixtures of ultracold CaF molecules and Rb atoms in a magnetic trap study their inelastic collisions. When the are prepared spin-stretched state component first rotationally excited state, they collide inelastically with rate coefficient k2=(6.6±1.5)×10−11 cm3/s at temperatures near 100 μK. attribute this to rotation-changing ground rotational we see no loss set an upper bound on spin-relaxation k2<5.8×10−12 95% confidence. compare these measurements results single-channel model...
Abstract The detection of variations fundamental constants the Standard Model would provide us with compelling evidence new physics, and could lift veil on nature dark matter energy. In this work, we discuss how a network atomic molecular clocks can be used to look for such unprecedented sensitivity over wide range time scales. This is precisely goal recently launched QSNET project: A measuring stability constants. will include state-of-the-art clocks, but also develop next-generation highly...
We show that an array of polar molecules interacting with Rydberg atoms is a promising hybrid system for scalable quantum computation. Quantum information stored in long-lived hyperfine or rotational states molecules, which interact indirectly through resonant dipole-dipole interactions atoms. A two-qubit gate based on this interaction has duration 1μs and achievable fidelity 99.9%. The little sensitivity to the motional particles—the can be thermal states, do not need trapped during...
A mechanism of magneto-optical trapping is revealed when the polarizations and detunings two components a laser are specially chosen, which provides convenient means to capture trap cold CaF or some other molecules that can be used in precise measurements tackle many fundamental physics questions.
We model sympathetic cooling of ground-state CaF molecules by ultracold Li and Rb atoms. The are moving in a microwave trap, while the atoms trapped magnetically. calculate differential elastic cross sections for CaF-Li CaF-Rb collisions, using Lennard-Jones potentials adjusted to give typical values $s$-wave scattering length. Together with trajectory calculations, these used simulate molecules, heating atoms, loss from trap. show that hard-sphere collision based on an energy-dependent...
Experiments with cold molecules usually begin a molecular source. We describe the construction and characteristics of cryogenic buffer gas source CaF molecules. The emits pulses typical duration 240 μs, mean speed about 150 m/s, flux 5×1010 per steradian pulse in single rotational state.
Measurements of the electron's electric dipole moment (eEDM) are demanding tests physics beyond Standard Model. We describe how ultracold YbF molecules could be used to improve precision eEDM measurements by two three orders magnitude. Using numerical simulations, we show combination magnetic focussing, two-dimensional transverse laser cooling, and frequency-chirped slowing, can produce an intense, slow, highly-collimated molecular beam. make a magneto-optical trap loaded into optical...