A search for varying fundamental constants using Hz-level frequency measurements of cold CH molecules

Abstract

Many modern theories predict that the fundamental constants depend on time, position, or the local density of matter. We develop a spectroscopic method for pulsed beams of cold molecules, and use it to measure the frequencies of microwave transitions in CH with accuracy down to 3 Hz. By comparing these frequencies with those measured from sources of CH in the Milky Way, we test the hypothesis that fundamental constants may differ between the high and low density environments of the Earth and the interstellar medium. For the fine structure constant we find Δα/α= (0.3 +/- 1.1)*10^{-7}, the strongest limit to date on such a variation of α. For the electron-to-proton mass ratio we find Δμ/μ= (-0.7 +/- 2.2) * 10^{-7}. We suggest how dedicated astrophysical measurements can improve these constraints further and can also constrain temporal variation of the constants.

8 pages, 3 figures

References in corpus (24)

• Chameleon Fields: Awaiting Surprises for Tests of Gravity in Space
• The fundamental constants and their variation: observational status and theoretical motivations
• Varying constants, Gravitation and Cosmology
• Detecting Dark Energy in Orbit -- the Cosmological Chameleon
• Indications of a spatial variation of the fine structure constant
• Environmental Dependence of Masses and Coupling Constants
• Cold Molecule Spectroscopy for Constraining the Evolution of the Fine Structure Constant
• New Limits on Coupling of Fundamental Constants to Gravity Using ${}^{87}$Sr Optical Lattice Clocks
• Stability of the proton-to-electron mass ratio
• The Fundamental Vibration of Molecular Hydrogen
• Bounds on fifth forces from precision measurements on molecules
• Methanol as a tracer of fundamental constants
• First measurement of Mg isotope abundances at high redshifts and accurate estimate of Delta alpha/alpha
• Bounds on the fine structure constant variability from FeII absorption lines in QSO spectra
• Searching for chameleon-like scalar fields with the ammonia method
• Searching for chameleon-like scalar fields with the ammonia method. II. Mapping of cold molecular cores in NH3 and HC3N lines
• Constraining the variation of fundamental constants at z ~ 1.3 using 21-cm absorbers
• $\Lambda$-doublet spectra of diatomic radicals and their dependence on fundamental constants
• An upper limit to the variation in the fundamental constants at redshift z = 5.2
• Precision measurements with polar molecules: the role of the black body radiation
• On the Variations of Fundamental Constants and AGN feedback in the QSO host galaxy RXJ0911.4+0551 at z=2.79
• Probing fundamental constant evolution with redshifted conjugate-satellite OH lines
• Sensitivity of rotational transitions in CH and CD to a possible variation of fundamental constants
• Searching for spatial variations of alpha^2/mu in the Milky Way

Cited by in corpus (55)

• Search for New Physics with Atoms and Molecules
• Laser cooling and slowing of CaF molecules
• Ultracold molecules for measuring the electron's electric dipole moment
• Optoelectrical cooling of polar molecules to sub-millikelvin temperatures
• Ultracold molecules for quantum simulation: rotational coherences in CaF and RbCs
• Laser cooling of molecules
• Perspective: Tipping the scales - search for drifting constants from molecular spectra
• Laser cooled molecules
• An intense, cold, velocity-controlled molecular beam by frequency-chirped laser slowing
• CO/H2, C/CO, OH/CO, and OH/O2 in Dense Interstellar Gas: From High Ionization to Low Metallicity
• High-precision methanol spectroscopy with a widely tunable SI-traceable frequency-comb-based mid-infrared QCL
• A buffer gas beam source for short, intense and slow molecular pulses
• Generalized auto-balanced Ramsey spectroscopy of clock transitions
• Progress and perspectives on composite laser-pulses spectroscopy for high-accuracy optical clocks
• Modeling sympathetic cooling of molecules by ultracold atoms
• A widely tunable 10-$\mu$m quantum cascade laser phase-locked to a state-of-the-art mid-infrared reference for precision molecular spectroscopy
• The minimally extended Varying Speed of Light (meVSL)
• Principles and design of a Zeeman-Sisyphus decelerator for molecular beams
• Fundamental constants and cosmic vacuum: the micro and macro connection
• Limits on the spatial variations of the electron-to-proton mass ratio in the Galactic plane
• Precision measurement of the ionization energy and quantum defects of 39K I
• High-resolution mid-infrared spectroscopy of buffer-gas-cooled methyltrioxorhenium molecules
• Ultracold ${}^{88}{\mathrm{Sr}}_2$ molecules in the absolute ground state
• Deceleration and trapping of ammonia molecules in a traveling wave decelerator
• Optimized cell geometry for buffer-gas-cooled molecular-beam sources
• Search for variation of fundamental constants: Strong enhancements in $X^2\Pi$ cations of dihalogens and hydrogen halides
• Measurement of the binding energy of ultracold ${}^{87}$Rb${}^{133}$Cs molecules using an offset-free optical frequency comb
• Method for traveling-wave deceleration of buffer-gas beams of CH
• Testing the weak equivalence principle by differential measurements of fundamental constants in the Magellanic Clouds
• Laser control of ultracold molecule formation: The case of RbSr
• Laser spectroscopy of aromatic molecules with optical cycling centers: strontium (I) phenoxides
• Optical Feshbach resonances and ground state molecule production in the RbHg system
• Microwave trap for atoms and molecules
• A high quality, efficiently coupled microwave cavity for trapping cold molecules
• Microwave spectroscopy of Lambda-doublet transitions in the ground state of CH
• High-resolution 'magic'-field spectroscopy on trapped polyatomic molecules
• Diatomic rovibronic transitions as potential probes for proton-to-electron mass ratio across cosmological time
• Sympathetic cooling and slowing of molecules with Rydberg atoms
• Laser spectroscopy of cold molecules
• Cavity Ring-down UV spectroscopy of the C${}^2{\Sigma }^{+}$-X${}^2\Pi$ electronic transition of CH
• Astrophysical constraints on the proton-to-electron mass ratio with FAST
• Ramsey-type microwave spectroscopy on CO ($a^3\Pi$)
• Enhancing radical molecular beams by skimmer cooling
• Trapping molecules on chips
• On the Stability of Fundamental Couplings in the Galaxy
• The evolution of CH in Planck Galactic Cold Clumps
• Searching for cosmological variation of the proton-to-electron mass ratio using a single $H_2$ system
• Cold CH radicals for laser cooling and trapping
• High-resolution spectroscopy of barium monofluoride: Odd isotopologues, hyperfine structure and isotope shifts
• Magnetic hyperfine structure constants of ${}^{137}$BaF in the ${}^2{\Pi }_{1/2}$ and ${}^2{\Pi }_{3/2}$ excited states
• Revisiting rotationally excited CH at radio wavelengths: A case study towards W51
• A sub-ppm upper limit on the cosmological variations of the fine structure constant alpha
• Electrostatic guiding of the methylidyne radical at cryogenic temperatures
• First Search for Low-Frequency CH with a Square Kilometre Array Precursor Telescope
• High-resolution spectroscopy on cold electrically trapped formaldehyde