Development of a new UHV/XHV pressure standard (cold atom vacuum standard)

Scherschligt, Julia; Fedchak, James A.; Barker, Daniel S.; Eckel, Stephen; Klimov, Nikolai N.; Makrides, Constantinos; Tiesinga, Eite

doi:10.1088/1681-7575/aa8a7b

Cited by 52 publications

(45 citation statements)

References 39 publications

(63 reference statements)

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“…More recently, researchers at NIST have estimated that they will achieve absolute pressure measurements with an uncertainty of 5% using a combination of trap loss measurements and ab initio calculations of cross sections for the Li + H 2 system. They proposed to extend this primary SI traceability to other species using a dynamic gas expansion system [18][19][20]. While systematic, this approach is limited to measurements of inert gases only.…”

Section: Qdu-based Metrologymentioning

confidence: 99%

Universality of quantum diffractive collisions and the quantum pressure standard

et al. 2019

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This work demonstrates that quantum diffractive collisions are governed by a universal law characterized by a single parameter that can be determined experimentally. Specifically, we report a quantitative form of the universal, cumulative energy distribution transferred to initially stationary sensor particles by quantum diffractive collisions. The characteristic energy scale corresponds to the localization length associated with the collision-induced quantum measurement, and the shape of the universal function is determined only by the analytic form of the interaction potential at long range. Using cold 87 Rb sensor atoms confined in a magnetic trap, we observe experimentally p QDU6 , the universal function specific to van der Waals collisions, and use it to realize a self-defining particle pressure sensor that can be used for any ambient gas. This provides the first primary and quantum definition of the Pascal, applicable to any species and therefore represents a fundamental advance for vacuum and pressure metrology. The quantum pressure standard realized here is compared with a state-of-the-art orifice flow standard transferred by an ionization gauge calibrated for N 2 . The pressure measurements agree at the 0.5% level. m d 4 2 t  º p s ̶ [4]. Here m t is the mass of the sensor particle and s ̶ is the thermally-averaged total collision cross section, including contributions from both elastic and inelastic scattering. We further demonstrate that s ̶ is independent of the short-range interaction between the colliding particles with van der Waals long-range interactions.It is well known that collisions resulting in small momentum transfer are dominated by quantum diffractive scattering [4,5]. Such collisions occur with small scattering angles 0 q  and are predominantly determined by OPEN ACCESS RECEIVED

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Section: Qdu-based Metrologymentioning

confidence: 99%

Universality of quantum diffractive collisions and the quantum pressure standard

et al. 2019

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“…On the highest level of vacuum metrology, optical ways of measurements are under development [12]. These use the determination of refractive index to measure vacuum pressures from about 1 Pa to 100 kPa, absorption spectroscopy for pressures below and magneto-optical traps for pressures in the UHV regime [13]. Most of these methods are fundamental and suitable as primary standards.…”

Section: Discussionmentioning

confidence: 99%

Vacuum metrology and its impact on research and industry

Jousten

2019

Vak Forsch Prax

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Summary By accurate vacuum measurement, it is possible to control processes in industry, to ensure the necessary environmental conditions for many experiments in science and research and to support the commercial relationship between manufacturers and users of vacuum equipment. The main task of vacuum metrology, the science of vacuum measurement, is to provide traceability of vacuum measurements to the SI. In recent years, also the characterization of vacuum by partial pressure analysis and outgassing rate measurement, and the dynamics of vacuum measurement became an issue for vacuum metrology.

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“…By incorporating fully quantum scattering calculations, it may be possible to use this pressure measurement technique as the basis of a primary pressure standard. Due to the months long trapping times possible with trapped ions, such a standard may have a significantly lower measurement floor than those based on neutral atoms [38].…”

Section: Contributionmentioning

confidence: 99%

Systematic uncertainty due to background-gas collisions in trapped-ion optical clocks

et al. 2019

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We describe a framework for calculating the frequency shift and uncertainty of trapped-ion optical atomic clocks caused by background-gas collisions, and apply this framework to an 27 Al + clock to enable a total fractional systematic uncertainty below 10 −18 . For this clock, with 38(19) nPa of room temperature H2 background gas, we find that collisional heating generates a non-thermal distribution of motional states with a mean time-dilation shift of order 10 −16 at the end of a 150 ms probe, which is not detected by sideband thermometry energy measurements. However, the contribution of collisional heating to the spectroscopy signal is highly suppressed and we calculate the BGC shift to be −0.6(2.4) × 10 −19 , where the shift is due to collisional heating time-dilation and the uncertainty is dominated by the worst case ±π/2 bound used for collisional phase shift of the 27 Al + superposition state. We experimentally validate the framework and determine the background-gas pressure in situ using measurements of the rate of collisions that cause reordering of mixed-species ion pairs.

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Development of a new UHV/XHV pressure standard (cold atom vacuum standard)

Cited by 52 publications

References 39 publications

Universality of quantum diffractive collisions and the quantum pressure standard

Universality of quantum diffractive collisions and the quantum pressure standard

Vacuum metrology and its impact on research and industry

Systematic uncertainty due to background-gas collisions in trapped-ion optical clocks

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