arXiv subjects

Nicholas R. Hutzler

Publications and source records attributed to Nicholas R. Hutzler.

50 records · Page 3Linked to original sources

arXiv2017

Precision Measurement of Time-Reversal Symmetry Violation with Laser-Cooled Polyatomic Molecules

Precision searches for time-reversal symmetry violating interactions in polar molecules are extremely sensitive probes of high energy physics beyond the Standard Model. To extend the reach of these probes into the PeV regime, long coherence times and large count rates are necessary. Recent advances in laser cooling of polar molecules offer one important tool -- optical trapping. However, the types of molecules that have been laser-cooled so far do not have the highly desirable combination of features for new physics searches, such as the ability to fully polarize and the existence of internal co-magnetometer states. We show that by utilizing the internal degrees of freedom present only in molecules with at least three atoms, these features can be attained simultaneously with molecules that have simple structure and are amenable to laser cooling and trapping.

physics.atom-ph↗

arXiv2017

Radio Frequency Magneto-Optical Trapping of CaF with High Density

We demonstrate significantly improved magneto-optical trapping of molecules using a very slow cryogenic beam source and RF modulated and DC magnetic fields. The RF MOT confines $1.1(3) \times 10^5$ CaF molecules at a density of $4(1) \times 10^6$ cm$^{-3}$, which is an order of magnitude greater than previous molecular MOTs. Near Doppler-limited temperatures of $340(20)$ $μ$K are attained. The achieved density enables future work to directly load optical tweezers and create optical arrays for quantum simulation.

physics.atom-ph↗

arXiv2017

One dimensional magneto-optical compression of a cold CaF molecular beam

We demonstrate with a RF-MOT the one dimensional, transverse magneto-optical compression of a cold beam of calcium monofluoride (CaF). By continually alternating the magnetic field direction and laser polarizations of the magneto-optical trap, a photon scattering rate of $2π\times$0.4 MHz is achieved. A 3D model for this RF-MOT, validated by agreement with data, predicts a 3D RF-MOT capture velocity for CaF of 5 m/s.

physics.atom-ph↗

arXiv2017

Ultracold Molecular Assembly

Chemical reactions can be surprisingly efficient at ultracold temperatures ( < 1mK) due to the wave nature of atoms and molecules. The study of reactions in the ultracold regime is a new research frontier enabled by cooling and trapping techniques developed in atomic and molecular physics. In addition, ultracold molecular gases that offer diverse molecular internal states and large electric dipolar interactions are sought after for studies of strongly interacting many-body quantum physics. Here we propose a new approach for producing ultracold molecules in the absolute internal and motional quantum ground state, where single molecules are assembled one by one from individual atoms. The scheme involves laser cooling, optical trapping, Raman sideband cooling, and coherent molecular state transfer. As a crucial initial step, we demonstrate quantum control of constituent atoms, including 3D ground-state cooling of a single Cs atom, in a simple apparatus. As laser technology advances to shorter wavelengths, additional atoms will be amenable to laser-cooling, allowing more diverse, and eventually more complex, molecules to be assembled with full quantum control.

physics.atom-ph↗

arXiv2016

Methods, Analysis, and the Treatment of Systematic Errors for the Electron Electric Dipole Moment Search in Thorium Monoxide

We recently set a new limit on the electric dipole moment of the electron (eEDM) (J. Baron et al., ACME collaboration, Science 343 (2014), 269-272), which represented an order-of-magnitude improvement on the previous limit and placed more stringent constraints on many CP-violating extensions to the Standard Model. In this paper we discuss the measurement in detail. The experimental method and associated apparatus are described, together with the techniques used to isolate the eEDM signal. In particular, we detail the way experimental switches were used to suppress effects that can mimic the signal of interest. The methods used to search for systematic errors, and models explaining observed systematic errors, are also described. We briefly discuss possible improvements to the experiment.

physics.atom-ph↗

arXiv2016

A low-temperature external cavity diode laser for broad wavelength tuning

We report on the design and characterization of a low-temperature external cavity diode laser (ECDL) system for broad wavelength tuning. The performance achieved with multiple diode models addresses the scarcity of commercial red laser diodes below 633 nm, which is a wavelength range relevant to spectroscopy of many molecules and ions. Using a combination of multiple-stage thermoelectric cooling and water cooling, the operating temperature of a laser diode is lowered to -64°C, more than 85°C below the ambient temperature. The laser system integrates temperature and diffraction grating feedback tunability for coarse and fine wavelength adjustments, respectively. For two different diode models, single-mode operation was achieved with 38 mW output power at 616.8 nm and 69 mW at 622.6 nm, more than 15 nm below their ambient temperature free-running wavelengths. The ECDL design can be used for diodes of any available wavelength, allowing individual diodes to be tuned continuously over tens of nanometers and extending the wavelength coverage of commercial laser diodes.

physics.atom-ph↗

arXiv2016

Eliminating light shifts in single-atom optical traps

Microscopically controlled neutral atoms in optical tweezers and lattices have led to exciting advances in the study of quantum information and quantum many-body systems. The light shifts of atomic levels from the trapping potential in these systems can result in detrimental effects such as fluctuating dipole force heating, inhomogeneous detunings, and inhibition of laser cooling, which limits the atomic species that can be manipulated. In particular, these light shifts can be large enough to prevent loading into optical tweezers directly from a magneto-optical trap. We present a general solution to these limitations by loading, cooling, and imaging single atoms with temporally alternating beams. Because this technique does not depend on any specific spectral properties, we expect it to enable the optical tweezer method to control nearly any atomic or molecular species that can be laser cooled and optically trapped. Furthermore, we present an analysis of the role of heating and required cooling for single atom tweezer loading.

physics.atom-ph↗

arXiv2016

Laser slowing of CaF molecules to near the capture velocity of a molecular MOT

Laser slowing of CaF molecules down to the capture velocity of a magneto-optical trap (MOT) for molecules is achieved. Starting from a two-stage buffer gas beam source, we apply frequency-broadened "white-light" slowing and observe approximately 6x10^4 CaF molecules with velocities near 10\,m/s. CaF is a candidate for collisional studies in the mK regime. This work represents a significant step towards magneto-optical trapping of CaF.

physics.atom-ph↗

arXiv2013

Order of Magnitude Smaller Limit on the Electric Dipole Moment of the Electron

The Standard Model (SM) of particle physics fails to explain dark matter and why matter survived annihilation with antimatter following the Big Bang. Extensions to the SM, such as weak-scale Supersymmetry, may explain one or both of these phenomena by positing the existence of new particles and interactions that are asymmetric under time-reversal (T). These theories nearly always predict a small, yet potentially measurable ($10^{-27}$-$10^{-30}$ $e$ cm) electron electric dipole moment (EDM, $d_e$), which is an asymmetric charge distribution along the spin ($\vec{S}$). The EDM is also asymmetric under T. Using the polar molecule thorium monoxide (ThO), we measure $d_e = (-2.1 \pm 3.7_\mathrm{stat} \pm 2.5_\mathrm{syst})\times 10^{-29}$ $e$ cm. This corresponds to an upper limit of $|d_e| < 8.7\times 10^{-29}$ $e$ cm with 90 percent confidence, an order of magnitude improvement in sensitivity compared to the previous best limits. Our result constrains T-violating physics at the TeV energy scale.

physics.atom-ph↗

arXiv2013

Advanced Cold Molecule Electron EDM

Measurement of a non-zero electric dipole moment (EDM) of the electron within a few orders of magnitude of the current best limit of |d_e| < 1.05 e -27 e cm would be an indication of physics beyond the Standard Model. The ACME Collaboration is searching for an electron EDM by performing a precision measurement of electron spin precession in the metastable H state of thorium monoxide (ThO) using a slow, cryogenic beam. We discuss the current status of the experiment. Based on a data set acquired from 14 hours of running time over a period of 2 days, we have achieved a 1-sigma statistical uncertainty of 1 e -28 e cm/T^(1/2), where T is the running time in days.

physics.atom-ph↗

arXiv2011

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

Beams of atoms and molecules are stalwart tools for spectroscopy and studies of collisional processes. The supersonic expansion technique can create cold beams of many species of atoms and molecules. However, the resulting beam is typically moving at a speed of 300-600 m/s in the lab frame, and for a large class of species has insufficient flux (i.e. brightness) for important applications. In contrast, buffer gas beams can be a superior method in many cases, producing cold and relatively slow molecules in the lab frame with high brightness and great versatility. There are basic differences between supersonic and buffer gas cooled beams regarding particular technological advantages and constraints. At present, it is clear that not all of the possible variations on the buffer gas method have been studied. In this review, we will present a survey of the current state of the art in buffer gas beams, and explore some of the possible future directions that these new methods might take.

physics.atom-ph↗

arXiv2011

Magnetic and electric dipole moments of the $H\ {}^3Δ_1$ state in ThO

The metastable $H \ {}^3Δ_1$ state in the thorium monoxide (ThO) molecule is highly sensitive to the presence of a CP-violating permanent electric dipole moment of the electron (eEDM). The magnetic dipole moment $μ_H$ and the molecule-fixed electric dipole moment $D_H$ of this state are measured in preparation for a search for the eEDM. The small magnetic moment $μ_H = 8.5(5) \times 10^{-3} \ μ_B$ displays the predicted cancellation of spin and orbital contributions in a ${}^3 Δ_1$ paramagnetic molecular state, providing a significant advantage for the suppression of magnetic field noise and related systematic effects in the eEDM search. In addition, the induced electric dipole moment is shown to be fully saturated in very modest electric fields ($<$ 10 V/cm). This feature is favorable for the suppression of many other potential systematic errors in the ThO eEDM search experiment.

physics.atom-ph↗

arXiv2011

A cryogenic beam of refractory, chemically reactive molecules with expansion cooling

Cryogenically cooled buffer gas beam sources of the molecule thorium monoxide (ThO) are optimized and characterized. Both helium and neon buffer gas sources are shown to produce ThO beams with high flux, low divergence, low forward velocity, and cold internal temperature for a variety of stagnation densities and nozzle diameters. The beam operates with a buffer gas stagnation density of ~10^15-10^16 cm^-3 (Reynolds number ~1-100), resulting in expansion cooling of the internal temperature of the ThO to as low as 2 K. For the neon (helium) based source, this represents cooling by a factor of about 10 (2) from the initial nozzle temperature of about 20 K (4 K). These sources deliver ~10^11 ThO molecules in a single quantum state within a 1-3 ms long pulse at 10 Hz repetition rate. Under conditions optimized for a future precision spectroscopy application [A C Vutha et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 074007], the neon-based beam has the following characteristics: forward velocity of 170 m/s, internal temperature of 3.4 K, and brightness of 3x10^11 ground state molecules per steradian per pulse. Compared to typical supersonic sources, the relatively low stagnation density of this source, and the fact that the cooling mechanism relies only on collisions with an inert buffer gas, make it widely applicable to many atomic and molecular species, including those which are chemically reactive, such as ThO.

physics.atom-ph↗

arXiv2010

Search for the electric dipole moment of the electron with thorium monoxide

The electric dipole moment of the electron (eEDM) is a signature of CP-violating physics beyond the Standard Model. We describe an ongoing experiment to measure or set improved limits to the eEDM, using a cold beam of thorium monoxide (ThO) molecules. The metastable $H {}^3Δ_1$ state in ThO has important advantages for such an experiment. We argue that the statistical uncertainty of an eEDM measurement could be improved by as much as 3 orders of magnitude compared to the current experimental limit, in a first-generation apparatus using a cold ThO beam. We describe our measurements of the $H$ state lifetime and the production of ThO molecules in a beam, which provide crucial data for the eEDM sensitivity estimate. ThO also has ideal properties for the rejection of a number of known systematic errors; these properties and their implications are described.

physics.atom-ph↗