Imperial College London

ProfessorMichaelTarbutt

Faculty of Natural SciencesDepartment of Physics

Professor of Experimental Physics
 
 
 
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Contact

 

+44 (0)20 7594 7741m.tarbutt

 
 
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Location

 

207Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

106 results found

Alauze X, Lim J, Trigatzis MA, Swarbrick S, Collings FJ, Fitch NJ, Sauer BE, Tarbutt MRet al., 2021, An ultracold molecular beam for testing fundamental physics, Quantum Science and Technology, Vol: 6

We use two-dimensional transverse laser cooling to produce an ultracold beam of YbF molecules. Through experiments and numerical simulations, we study how the cooling is influenced by the polarization configuration, laser intensity, laser detuning and applied magnetic field. The ultracold part of the beam contains more than 2 105 molecules per shot and has a temperature below 200 μK, and the cooling yields a 300-fold increase in the brightness of the beam. The method can improve the precision of experiments that use molecules to test fundamental physics. In particular, the beam is suitable for measuring the electron electric dipole moment with a statistical precision better than 10-30 e cm.

Journal article

Jurgilas S, Chakraborty A, Rich C, Sauer B, Frye MD, Hutson JM, Tarbutt Met al., 2021, Collisions in a dual-species magneto-optical trap of molecules and atoms, New Journal of Physics, Vol: 23, ISSN: 1367-2630

We study inelastic collisions between CaF molecules and ⁸⁷Rb atoms in a dual-species magneto-optical trap. The presence of atoms increases the loss rate of molecules from the trap. By measuring the loss rates and density distributions, we determine a collisional loss rate coefficient k₂ = (1.43 ± 0.29) × 10‾¹⁰cm³/s at a temperature of 2.4 mK. We show that this is not substantially changed by light-induced collisions or by varying the populations of excited-state atoms and molecules. The observed loss rate is close to the universal rate expected in the presence of fast loss at short range, and can be explained by rotation-changing collisions in the ground electronic state.

Journal article

Jurgilas S, Chakraborty A, Rich CJH, Caldwell L, Williams HJ, Fitch NJ, Sauer BE, Frye MD, Hutson JM, Tarbutt MRet al., 2021, Collisions between Ultracold Molecules and Atoms in a Magnetic Trap, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007

Journal article

Caldwell L, Tarbutt M, 2021, General approach to state-dependent optical tweezer traps for polar molecules, Physical Review Research, Vol: 3, ISSN: 2643-1564

State-dependent optical tweezers can be used to trap a pair of molecules with a separation much smaller than the wavelength of the trapping light, greatly enhancing the dipole-dipole interaction between them. Here we describe a general approach to producing these state-dependent potentials using the tensor part of the ac Stark shift and show how it can be used to carry out two-qubit gates between pairs of molecules. The method is applicable to broad classes of molecules including bialkali molecules produced by atom association and those amenable to direct laser cooling.

Journal article

Fitch NJ, Lim J, Hinds EA, Sauer BE, Tarbutt MRet al., 2021, Methods for measuring the electron's electric dipole moment using ultracold YbF molecules, QUANTUM SCIENCE AND TECHNOLOGY, Vol: 6, ISSN: 2058-9565

Journal article

Caldwell L, Tarbutt MR, 2020, Enhancing dipolar interactions between molecules using state-dependent optical tweezer traps, Physical Review Letters, Vol: 125, Pages: 243201 – 1-243201 – 6, ISSN: 0031-9007

We show how state-dependent optical potentials can be used to trap a pair of molecules in different internal states at a separation much smaller than the wavelength of the trapping light. This close spacing greatly enhances thedipole-dipole interaction and we show how it can be used to implement two-qubit gates between molecules that are 100 times faster than existing protocols and than rotational coherence times already demonstrated. We analyze complications due to hyperfine structure, tensor light shifts, photon scattering and collisional loss, and conclude that none is a barrier to implementing the scheme.

Journal article

Hughes M, Frye MD, Sawant R, Bhole G, Jones JA, Cornish SL, Tarbutt MR, Hutson JM, Jaksch D, Mur-Petit Jet al., 2020, Robust entangling gate for polar molecules using magnetic and microwave fields, Physical Review A, Vol: 101, Pages: 062308-1-062308-12, ISSN: 2469-9926

Polar molecules are an emerging platform for quantum technologies based on their long-range electric dipole–dipole interactions, which open new possibilities for quantum information processing and the quantum simulation of strongly correlated systems. Here, we use magnetic and microwave fields to design a fast entangling gate with >0.999 fidelity and which is robust with respect to fluctuations in the trapping and control fields and to small thermal excitations. These results establish the feasibility to build a scalable quantum processor with a broad range of molecular species in optical-lattice and optical-tweezers setups.

Journal article

Ho C, Devlin JA, Rabey I, Yzombard P, Lim J, Wright S, Fitch N, Hinds EA, Tarbutt MR, Sauer BEet al., 2020, New techniques for a measurement of the electron's electric dipole moment, New Journal of Physics, Vol: 22, ISSN: 1367-2630

The electric dipole moment of the electron (eEDM) can be measured with high precision using heavy polar molecules. In this paper, we report on a series of new techniques that have improved the statistical sensitivity of the YbF eEDM experiment. We increase the number of molecules participating in the experiment by an order of magnitude using a carefully designed optical pumping scheme. We also increase the detection efficiency of these molecules by another order of magnitude using an optical cycling scheme. In addition, we show how to destabilise dark states and reduce backgrounds that otherwise limit the efficiency of these techniques. Together, these improvements allow us to demonstrate a statistical sensitivity of 1.8 x 10⁻²⁸ e cm after one day of measurement, which is 1.2 times the shot-noise limit. The techniques presented here are applicable to other high-precision measurements using molecules.

Journal article

Ho C, Devlin J, Rabey I, Yzombard P, Lim J, Wright S, Fitch N, Hinds E, Tarbutt M, Sauer Bet al., 2020, New techniques for a measurement of the electron's electric dipole moment, New Journal of Physics, ISSN: 1367-2630

The electric dipole moment of the electron (eEDM) can be measured with high precision using heavy polar molecules. In this paper, we report on a series of new techniques that have improved the statistical sensitivity of the YbF eEDM experiment. We increase the number of molecules participating in the experiment by an order of magnitude using a carefully designed optical pumping scheme. We also increase the detection efficiency of these molecules by another order of magnitude using an optical cycling scheme. In addition, we show how to destabilise dark states and reduce backgrounds that otherwise limit the efficiency of these techniques. Together, these improvements allow us to demonstrate a statistical sensitivity of 1.8 x 10⁻²⁸ e cm after one day of measurement, which is 1.2 times the shot-noise limit. The techniques presented here are applicable to other high-precision measurements using molecules.

Journal article

Caldwell L, Tarbutt MR, 2020, Sideband cooling of molecules in optical traps, Publisher: AMER PHYSICAL SOC

Working paper

Caldwell L, Tarbutt M, 2020, Sideband cooling of molecules in optical traps, Physical Review & Research, Vol: 2, ISSN: 2643-1564

Sideband cooling is a popular method for cooling atoms to the ground state of an optical trap. Applying the same method to molecules requires a number of challenges to be overcome. Strong tensor Stark shifts in molecules cause the optical trapping potential, and corresponding trap frequency, to depend strongly on rotational, hyper fine and Zeeman state. Consequently, transition frequencies depend on the motional quantum number and there are additional heating mechanisms, either of which can be fatal for an eff ective sideband cooling scheme. We develop the theory of sideband cooling in state-dependent potentials, and derive an expression for the heating due to photon scattering. We calculate the ac Stark shifts of molecular states in the presence of a magnetic field, and for any polarization. We show that the complexity of sideband cooling can be greatly reduced by applying a large magnetic fi eld to eliminate electron- and nuclear-spin degrees of freedom from the problem. We consider how large the magnetic field needs to be, show that heating can be managedsuffi ciently well, and present a simple recipe for cooling to the ground state of motion.

Journal article

Caldwell L, Williams H, Fitch N, Aldegunde J, Hutson J, Sauer B, Tarbutt Met al., 2020, Long rotational coherence times of molecules in a magnetic trap, Physical Review Letters, Vol: 124, ISSN: 0031-9007

Polar molecules in superpositions of rotational states exhibit long-range dipolar interactions, but maintaining their coherence in a trapped sample is a challenge. We present calculations that show many laser-coolable molecules have convenient rotational transitions that are exceptionally insensitive to magnetic fi elds. We verify this experimentally for CaF where we find a transition with sensitivity below 5 HzG‾¹ and use it to demonstrate a rotational coherence time of 6.4(8) ms in a magnetic trap. Simulations suggest it is feasible to extend this to > 1 s using a smaller cloud in abiased magnetic trap.

Journal article

Sawant R, Blackmore JA, Gregory PD, Mur-Petit J, Jaksch D, Aldegunde J, Hutson JM, Tarbutt MR, Cornish SLet al., 2020, Ultracold polar molecules as qudits, New Journal of Physics, Vol: 22, Pages: 1-12, ISSN: 1367-2630

We discuss how the internal structure of ultracold molecules, trapped in the motional ground state of optical tweezers, can be used to implement qudits. We explore the rotational, fine and hyperfine structure of 40Ca19F and 87Rb133Cs, which are examples of molecules with 2Σ and 1Σ electronic ground states, respectively. In each case we identify a subset of levels within a single rotational manifold suitable to implement a four-level qudit. Quantum gates can be implemented using two-photon microwave transitions via levels in a neighboring rotational manifold. We discuss limitations to the usefulness of molecular qudits, arising from off-resonant excitation and decoherence. As an example, we present a protocol for using a molecular qudit of dimension d = 4 to perform the Deutsch algorithm.

Journal article

Wright S, Wall T, Tarbutt M, 2019, Microwave trap for atoms and molecules, Physical Review Research, Vol: 1, ISSN: 2643-1564

We demonstrate a trap that confines polarizable particles around the antinode of a standing-wave microwave field. The trap relies only on the polarizability of the particles far from any resonances, so can trap a wide variety of atoms and molecules in a wide range of internal states, including the ground state. The trap has a volume of about 10 cm³, and a depth approaching 1K for many polarmolecules. We measure the trap properties using ⁷Li atoms, showing that when the input microwave power is 610W, the atoms remain trapped with a 1/e lifetime of 1.76(12) s, oscillating with an axial frequency of 28.55(5) Hz and a radial frequency of 8.81(8) Hz. The trap could be loaded with slowmolecules from a range of available sources, and is particularly well suited to sympathetic cooling and evaporative cooling of molecules.

Journal article

Caldwell L, Devlin J, Williams H, Fitch N, Hinds E, Sauer B, Tarbutt Met al., 2019, Deep Laser Cooling and Efficient Magnetic Compression of Molecules, Physical Review Letters, Vol: 123, ISSN: 0031-9007

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 a widely applicable method that can reach the recoil limit or below. We demonstrate and characterise the method experimentally, reachinga temperature of 5.4(7) μK. We solve a general problem of measuring low temperatures for large clouds by rotating the phase-space distribution and then directly imaging the complete velocity distribution. Using the same phase-space rotation method, we rapidly compress the cloud. Applying the cooling method a second time, we compress both the position and velocity distributions.

Journal article

Tarbutt MR, 2019, Laser cooling of molecules, Contemporary Physics, Vol: 59, Pages: 356-376, ISSN: 0010-7514

Recently, laser cooling methods have been extended from atoms to molecules. The complex rotational and vibrational energy level structure of molecules makes laser cooling difficult, but these difficulties have been overcome and molecules have now been cooled to a few microkelvin and trapped for several seconds. This opens many possibilities for applications in quantum science and technology, controlled chemistry, and tests of fundamental physics. This article explains how molecules can be decelerated, cooled and trapped using laser light, reviews the progress made in recent years, and outlines some future applications.

Journal article

Cournol A, Manceau M, Pierens M, Lecordier L, Tran DBA, Santagata R, Argence B, Goncharov A, Lopez O, Abgrall M, Le Coq Y, Le Targat R, Martinez HA, Lee WK, Xu D, Pottie P-E, Hendricks RJ, Wall TE, Bieniewska JM, Sauer BE, Tarbutt MR, Amy-Klein A, Tokunaga SK, Darquie Bet al., 2019, A new experiment to test parity symmetry in cold chiral molecules using vibrational spectroscopy, QUANTUM ELECTRONICS, Vol: 49, Pages: 288-292, ISSN: 1063-7818

Journal article

Blackmore JA, Caldwell L, Gregory PD, Bridge EM, Sawant R, Aldegunde J, Mur-Petit J, Jaksch D, Hutson JM, Sauer BE, Tarbutt MR, Cornish SLet al., 2019, Ultracold molecules for quantum simulation: rotational coherences in CaF and RbCs, Quantum Science and Technology, Vol: 4, ISSN: 2058-9565

Polar molecules offer a new platform for quantum simulation of systems with long-range interactions, based on the electrostatic interaction between their electric dipole moments. Here, we report the development of coherent quantum state control using microwave fields in 40Ca19F and 87Rb133Cs molecules, a crucial ingredient for many quantum simulation applications. We perform Ramsey interferometry measurements with fringe spacings of ~1 kHz and investigate the dephasing time of a superposition of N = 0 and N = 1 rotational states when the molecules are confined. For both molecules, we show that a judicious choice of molecular hyperfine states minimises the impact of spatially varying transition-frequency shifts across the trap. For magnetically trapped 40Ca19F we use a magnetically insensitive transition and observe a coherence time of 0.61(3) ms. For optically trapped 87Rb133Cs we exploit an avoided crossing in the AC Stark shifts and observe a maximum coherence time of 0.75(6) ms.

Journal article

Devlin J, Tarbutt M, 2018, Laser cooling and magneto-optical trapping of molecules analyzed using optical Bloch equations and the Fokker-Planck-Kramers equation, Physical Review A, Vol: 98, ISSN: 1050-2947

We study theoretically the behavior of laser-cooled calcium monofluoride (CaF) molecules in an optical molasses and magneto-optical trap (MOT), and compare our results to recent experiments. We use multilevel optical Bloch equations to estimate the force and the diffusion constant, followed by a Fokker-Planck-Kramers equation to calculate the time evolution of the velocity distribution. The calculations are done in three dimensions, and we include all the relevant energy levels of the molecule and all the relevant frequency components of the light. Similar to simpler model systems, the velocity-dependent force curve exhibits Doppler and polarization-gradient forces of opposite signs. We show that the temperature of the MOT is governed mainly by the balance of these two forces. Our calculated MOT temperatures and photon scattering rates are in broad agreement with those measured experimentally over a wide range of parameters. In a blue-detuned molasses, the temperature is determined by the balance of polarization-gradient cooling, and heating due to momentum diffusion, with no significant contribution from Doppler heating. In the molasses, we calculate a damping rate similar to the measured one, and steady-state temperatures that have the same dependence on laser intensity and applied magnetic field as measured experimentally, but are consistently a few times smaller than measured. We attribute the higher temperatures in the experiments to fluctuations of the dipole force which are not captured by our model. We show that the photon scattering rate is strongly influenced by the presence of dark states in the system, but that the scattering rate does not go to zero even for stationary molecules because of the transient nature of the dark states.

Journal article

Jarvis K, Sauer B, Tarbutt M, 2018, Characteristics of unconventional Rb magneto-optical traps, Physical Review A, Vol: 98, ISSN: 1050-2947

We study several new magneto-optical trapping configurations in ⁸⁷Rb. These unconventional MOTs all use type-II transitions, where the angular momentum of the ground state is greater than or equal to that of the excited state. Some use red-detuned light, and others blue-detuned light. The properties of these MOTs are strongly influenced by the balance between opposing Doppler and Sisyphus forces, and vary widely from one configuration to another. In the blue-detuned MOT, Sisyphus cooling dominates over Doppler heating for all relevant speeds and magnetic fields. We measure the capture velocity of this MOT as a function of intensity and detuning, finding a maximum of 3.8 ± 0.1 m/s. Atomic densities are particularly high in the blue-detuned MOT, and its lifetime is limited by collisions between the trapped atoms. We present measurements of the loss rate due to these ultracold collisions as a function of laser intensity and detuning. In the red-detuned MOTs, Sisyphus heating dominates at low speeds and Doppler cooling at higher speeds. Consequently, temperatures in the red-detuned MOTs are up to a thousand times higher than in the blue-detuned MOTs. One MOT forms large ring structures, with no density at the centre, showing how atoms driven towards a non-zero equilibrium speed remain trapped by orbiting around the centre. Another MOT demonstrates that magnetic mixing of the excited-state hyperfine levels can be an important mechanism in type-II MOTs.

Journal article

Williams HJ, Caldwell L, Fitch NJ, Truppe S, Rodewald J, Hinds EA, Sauer BE, Tarbutt MRet al., 2018, Magnetic trapping and coherent control of laser-cooled molecules, Physical Review Letters, Vol: 120, ISSN: 0031-9007

We demonstrate coherent microwave control of the rotational, hyperfine and Zeeman states of ultracold CaF molecules, and the magnetic trapping of these molecules in a single, selectable quantum state. We trap about 5 X 10³ molecules for almost 2s at a temperature of 70(8) μK and a density of 1.2 X 10⁵ cm⁻³. We measure the state-specific loss rate due to collisions with background helium.

Journal article

Lim J, Almond J, Trigatzis M, Devlin J, Fitch N, Sauer B, Tarbutt M, Hinds Eet al., 2018, Laser cooled YbF molecules for measuring the electron's electric dipole moment, Physical Review Letters, Vol: 120, ISSN: 0031-9007

We demonstrate one-dimensional sub-Doppler laser cooling of a beam of YbF molecules to 100 μK. This is a key step towards a measurement of the electron's electric dipole moment using ultracold molecules. We compare the effectiveness of magnetically-assisted and polarization-gradient sub-Doppler cooling mechanisms. We model the experiment and fi nd good agreement with our data.

Journal article

Jarvis KN, Devlin JA, Wall TE, Sauer BE, Tarbutt MRet al., 2018, Blue-detuned magneto-optical trap, Physical Review Letters, Vol: 120, ISSN: 0031-9007

We present the properties and advantages of a new magneto-optical trap (MOT) where blue- detuned light drives ‘type-II’ transitions that have dark ground states. Using ⁸⁷Rb, we reach a radiation-pressure-limited density exceeding 10¹¹ cm⁻³ and a temperature below 30 μK. The phase-space density is higher than in normal atomic MOTs, and a million times higher than comparable red-detuned type-II MOTs, making the blue-detuned MOT particularly attractive for molecular MOTs which rely on type-II transitions. The loss of atoms from the trap is dominated by ultracold collisions between Rb atoms. For typical trapping conditions, we measure a loss rate of 1.8(4) × 10⁻¹⁰ cm³ s⁻¹.

Journal article

Truppe S, Williams HJ, Hambach M, Caldwell L, Fitch NJ, Hinds EA, Sauer BE, Tarbutt MRet al., 2017, Molecules cooled below the Doppler limit, Nature Physics, Vol: 13, Pages: 1173-1176, ISSN: 1745-2473

The ability to cool atoms below the Doppler limit -- the minimum temperaturereachable by Doppler cooling -- has been essential to most experiments withquantum degenerate gases, optical lattices and atomic fountains, among manyother applications. A broad set of new applications await ultracold molecules,and the extension of laser cooling to molecules has begun. A molecularmagneto-optical trap has been demonstrated, where molecules approached theDoppler limit. However, the sub-Doppler temperatures required for mostapplications have not yet been reached. Here we cool molecules to 50 uK, wellbelow the Doppler limit, using a three-dimensional optical molasses. Theseultracold molecules could be loaded into optical tweezers to trap arbitraryarrays for quantum simulation, launched into a molecular fountain for testingfundamental physics, and used to study ultracold collisions and ultracoldchemistry.

Journal article

Williams H, Truppe S, Hambach M, Caldwell L, Fitch N, Hinds E, Sauer B, Tarbutt Met al., 2017, Characteristics of a magneto-optical trap of molecules, New Journal of Physics, Vol: 19, ISSN: 1367-2630

We present the properties of a magneto-optical trap (MOT) of CaFmolecules. We study the process of loading the MOT from a decelerated bu er-gas-cooled beam, and how best to slow this molecular beam in order to capture the most molecules. We determine how the number of molecules, the photon scattering rate, the oscillation frequency, damping constant, temperature, cloud size and lifetime depend on the key parameters of the MOT, especially the intensity and detuning of the main cooling laser. We compare our results to analytical and numerical models, to the properties of standard atomic MOTs, and to MOTs of SrF molecules. We load up to 2 x 10⁴ molecules, and measure a maximum scattering rate of 2.5 x 10⁶ s⁻¹ per molecule, a maximum oscillation frequency of 100 Hz, a maximum damping constant of 500 s⁻¹, and a minimum MOT rms radius of 1.5 mm. A minimum temperature of 730 μK is obtained by ramping down the laser intensity to low values. The lifetime, typically about 100 ms, is consistent with a leak out of the cooling cycle with a branching ratio of about 6 x 10⁻⁶. The MOT has a capture velocity of about 11 m/s.

Journal article

Truppe S, Hambach M, Skoff S, Bulleid N, Bumby J, Hendricks RJ, Hinds EA, Sauer BE, Tarbutt MRet al., 2017, A buffer gas beam source for short, intense and slow molecular pulses, Journal of Modern Optics, Vol: 65, Pages: 246-254, ISSN: 0950-0340

Experiments with cold molecules usually begin with a molecular source. We describe the construction and characteristics of a cryogenic buff er gas source of CaF molecules. The source emits pulses with a typical duration of 240 μs, a mean speed of about 150 m/s, and a flux of 5x 10¹⁰ molecules per steradian per pulse in a single rotational state.

Journal article

LIM J, Almond J, Tarbutt MR, Nguyen DT, Steimle TCet al., 2017, The [557]-X²∑⁺ and [561]- X²∑⁺ bands of ytterbium fluoride,¹⁷⁴YbF, Journal of Molecular Spectroscopy, Vol: 338, Pages: 81-90, ISSN: 1096-083X

The [557] - X2Σ+(v = 0, 1, 2, 3) and the [561] - X2Σ+ (v = 2) visible electronic transitions of YbF have been recorded at a near-natural linewidth spectral resolution using both supersonically cooled and buffer-gas cooled beams. The 174YbF isotopologue spectral features were analyzed to produce a new set of spectroscopic parameters for the X2Σ+(v = 2), X2Σ+(v = 3), [557], and [561] states. This study will facilitate ongoing work to produce ultracold YbF molecules by laser cooling in order to improve measurements of the electron’s electric dipole moment.

Journal article

Tokunaga SK, Hendricks RJ, Tarbutt MR, Darquie Bet al., 2017, High-resolution mid-infrared spectroscopy of buffer-gas-cooled methyltrioxorhenium molecules, New Journal of Physics, Vol: 19, ISSN: 1367-2630

We demonstrate cryogenic buffer-gas cooling of gas-phase methyltrioxorhenium (MTO). This molecule is closely related to chiral organometallic molecules where the parity-violating energy differences between enantiomers is measurable. The molecules are produced with a rotational temperature of approximately 6 K by laser ablation of an MTO pellet inside a cryogenic helium buffer gas cell. Facilitated by the low temperature, we demonstrate absorption spectroscopy of the 10.2 μm antisymmetric Re=O stretching mode of MTO with a resolution of 8 MHz and a frequency accuracy of 30 MHz. We partially resolve the hyperfine structure and measure the nuclear quadrupole coupling of the excited vibrational state. Our ability to produce dense samples of complex molecules of this type at low temperatures represents a key step towards a precision measurement of parity violation in a chiral species.

Journal article

Truppe S, Williams HJ, Fitch NJ, Hambach M, Wall TE, Hinds EA, Sauer BE, Tarbutt MRet al., 2017, An intense, cold, velocity-controlled molecular beam by frequency-chirped laser slowing, NEW JOURNAL OF PHYSICS, Vol: 19, ISSN: 1367-2630

Using frequency-chirped radiation pressure slowing, we precisely control the velocity of a pulsed CaF molecular beam down to a few m s–1, compressing its velocity spread by a factor of 10 while retaining high intensity: at a velocity of 15 m s–1 the flux, measured 1.3 m from the source, is 7 × 105 molecules per cm2 per shot in a single rovibrational state. The beam is suitable for loading a magneto-optical trap or, when combined with transverse laser cooling, improving the precision of spectroscopic measurements that test fundamental physics. We compare the frequency-chirped slowing method with the more commonly used frequency-broadened slowing method.

Journal article

Asselin P, Berger Y, Huet TR, Margules L, Motiyenko R, Hendricks RJ, Tarbutt MR, Tokunaga SK, Darquie Bet al., 2017, Characterising molecules for fundamental physics: an accurate spectroscopic model of methyltrioxorhenium derived from new infrared and millimetre-wave measurements, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 19, Pages: 4576-4587, ISSN: 1463-9076

Precise spectroscopic analysis of polyatomic molecules enables many striking advances in physical chemistry and fundamental physics. We use several new high-resolution spectroscopic devices to improve our understanding of the rotational and rovibrational structure of methyltrioxorhenium (MTO), the achiral parent of a family of large oxorhenium compounds that are ideal candidate species for a planned measurement of parity violation in chiral molecules. Using millimetre-wave and infrared spectroscopy in a pulsed supersonic jet, a cryogenic buffer gas cell, and room temperature absorption cells, we probe the ground state and the Re[double bond, length as m-dash]O antisymmetric and symmetric stretching excited states of both CH3187ReO3 and CH3185ReO3 isotopologues in the gas phase with unprecedented precision. By extending the rotational spectra to the 150–300 GHz range, we characterize the ground state rotational and hyperfine structure up to J = 43 and K = 41, resulting in refinements to the rotational, quartic and hyperfine parameters, and the determination of sextic parameters and a centrifugal distortion correction to the quadrupolar hyperfine constant. We obtain rovibrational data for temperatures between 6 and 300 K in the 970–1015 cm−1 range, at resolutions down to 8 MHz and accuracies of 30 MHz. We use these data to determine more precise excited-state rotational, Coriolis and quartic parameters, as well as the ground-state centrifugal distortion parameter DK of the 187Re isotopologue. We also account for hyperfine structure in the rovibrational transitions and hence determine the upper state rhenium atom quadrupole coupling constant eQq′.

Journal article

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