A search for sidereal variations in the frequency difference between co-located 129 Xe and 3 He Zeeman masers sets the most stringent limit to date on leading-order Lorentz and CPT violation involving the neutron, consistent with no effect at the level of 10 231 GeV. PACS numbers: 06.30.Ft, 11.30.Cp, 11.30.Er, 84.40.Ik Lorentz symmetry is a fundamental feature of modern descriptions of nature, including both the standard model of particle physics and general relativity. However, these realistic theories are believed to be the low-energy limit of a single fundamental theory at the Planck scale. Even if the underlying theory is Lorentz invariant, spontaneous symmetry breaking might result in small apparent violations of Lorentz invariance at an observable level. Experimental investigations of the validity of Lorentz symmetry therefore provide valuable tests of the framework of modern theoretical physics.Clock-comparison experiments [1-6] serve as sensitive probes of rotation invariance and hence of Lorentz symmetry, essentially by bounding the frequency variation of a clock as its orientation changes. In practice, the most precise limits are obtained by comparing the frequencies of two different co-located clocks as they rotate with the Earth. Typically, the clocks are electromagnetic signals emitted or absorbed on hyperfine or Zeeman transitions.Here, we report on a search for sidereal variations in the frequency of co-located 129 Xe and 3 He masers, both operating on nuclear spin-1͞2 Zeeman transitions. In the context of a general standard-model extension allowing for the possibility of Lorentz and CPT violation [7,8], the 129 Xe͞ 3 He-maser experiment sets the most stringent limit to date on leading-order Lorentz and CPT violation of the neutron: about 10 231 GeV, or more than 6 times better than the best previous measurements [9].The standard-model extension used to interpret this experiment emerges from any underlying theory that reduces at low energy to the standard model and contains spontaneous Lorentz violation [10]. For example, this might occur in string theory [11]. The standard-model extension maintains theoretically desirable properties of the usual standard model [8] [22,23]. A reanalysis by Adelberger, Gundlach, Heckel, and co-workers of existing data from a spin-polarized torsion-pendulum experiment [24,25] sets the most stringent bound to date on Lorentz and CPT violation of the electron, at about 10 228 GeV [26]. A recent Lorentzsymmetry test using hydrogen masers searched for hydrogen Zeeman-frequency sidereal variations, placing a bound on Lorentz violation at the level of 10 227 GeV [27]. Together with the results of Ref. [26], this implies an improved clean limit of 10 227 GeV on Lorentz-violating couplings involving the proton. Also, the KTeV experiment at Fermilab and the OPAL and DELPHI collaborations at CERN have constrained possible Lorentz-and CPT-violating effects in the K and B d systems [28,29].The design and operation of the two-species 129 Xe͞ 3 He maser has been discussed in r...

There was a factor of 2 omitted in the conversion of the experimental result into a limit on parameters of the standard-model extension. Therefore, the measured value of R 53 45 nHz correctly translates into a value ofb b n ? 6:4 5:4 10 ÿ32 GeV, which is smaller than the published value by a factor of 2.

We present a new measurement constraining Lorentz and CPT violation of the proton using a hydrogen maser double resonance technique. A search for hydrogen Zeeman frequency variations with a period of the sidereal day (23.93 h) sets a clean limit on violation of Lorentz and CPT symmetry of the proton at the 10 −27 GeV level.

A search for an annual variation of a daily sidereal modulation of the frequency difference between colocated 129Xe and 3He Zeeman masers sets a stringent limit on boost-dependent Lorentz and CPT violation involving the neutron, consistent with no effect at the level of 150 nHz. In the framework of the general standard-model extension, the present result provides the first clean test for the fermion sector of the symmetry of spacetime under boost transformations at a level of 10(-27) GeV.

We demonstrate light-pulse atom interferometry with large-momentum-transfer atom optics based on stimulated Raman transitions and frequency-swept adiabatic rapid passage. Our atom optics have produced momentum splittings of up to 30 photon recoil momenta in an acceleration-sensitive interferometer for laser cooled atoms. We experimentally verify the enhancement of phase shift per unit acceleration and characterize interferometer contrast loss. By forgoing evaporative cooling and velocity selection, this method lowers the atom shot-noise-limited measurement uncertainty and enables large-area atom interferometry at higher data rates. DOI: 10.1103/PhysRevLett.115.103001 PACS numbers: 37.25.+k, 03.75.Be, 03.75.Dg Light-pulse atom interferometry (LPAI) is a preeminent method for precision measurements of inertial forces [1,2] and fundamental physical constants [3,4]. Highly sensitive LPAI systems may be an enabling technology for nextgeneration inertial navigators [5][6][7], gravitational wave detectors [8], and tests of the equivalence principle [9]. Nevertheless, many light-pulse atom interferometers are presently limited by atom beam splitters and mirrors that create small momentum separations (two photon recoil momenta) between diffracting wave packets. The sensitivity of these interferometers typically increases with the effective area enclosed by the interfering wave packets [10]. Since this area is proportional to momentum separation, sensitivity can be enhanced using atom optics that generate large momentum transfer (LMT). Previous demonstrations of atom interferometry with LMT atom optics have taken several approaches, including sequential application of stimulated Raman transitions [11,12], Raman composite pulses [13], and stimulated Raman adiabatic rapid passage (STIRAP) pulses [14], as well as application of multiphoton-Bragg transitions [15][16][17], and Bloch oscillations in an optical lattice [18,19].In most of these demonstrations, cold atoms from a magneto-optical trap (MOT) were either evaporatively cooled or velocity selected-both of which typically discard >90% of the original atom sample. A reduced atom number is detrimental to atom shot-noise-limited measurement uncertainty and to operation at fast data rates. A slower data rate results because, following every measurement cycle, the steady-state atom number in the MOT must be recovered primarily from roomtemperature atoms. When cold atoms are recaptured, however, fewer atoms must be loaded from the roomtemperature background vapor, thus allowing the data rate to be increased above 100 Hz [20]. High data rates are crucial for atom interferometric measurements of dynamic signals, such as rapidly varying accelerations and rotations of moving platforms, as well as strains from high frequency (∼10 Hz) gravitational waves [8,19]. The fastest data rates with evaporative cooling have been limited to ≤1.3 Hz [21]; velocity selection at high data rates requires the added complexity of a 2D MOT to maintain atom number [22].In this Letter, we demonstra...