57 research outputs found
State of the art in the determination of the fine structure constant and the ratio
The fine structure constant and the ratio between
the Planck constant and the unified atomic mass are keystone constants for the
determination of other fundamental physical constants, especially the ones
involved in the framework of the future International System of units. This
paper presents how these two constants, which can be deduced from one another,
are measured. We will present in detail the measurement of
performed by atomic interferometry at the Laboratoire Kastler Brossel in Paris.
This type of measurement also allows a test of the standard model to be carried
out with unparalleled accuracy.Comment: arXiv admin note: text overlap with arXiv:1309.339
Atom interferometry based on light pulses : application to the high precision measurement of the ratio h/m and the determination of the fine structure constant
In this paper we present a short overview of atom interferometry based on
light pulses. We discuss different implementations and their applications for
high precision measurements. We will focus on the determination of the ratio
h/m of the Planck constant to an atomic mass. The measurement of this quantity
is performed by combining Bloch oscillations of atoms in a moving optical
lattice with a Ramsey-Bord\'e interferometer
Precise determination of h/m_Rb using Bloch oscillations and atomic interferometry: a mean to deduce the fine structure constant
We use Bloch oscillations to transfer coherently many photon momenta to
atoms. Then we can measure accurately the ratio h/m_Rb and deduce the fine
structure constant alpha. The velocity variation due to the Bloch oscillations
is measured thanks to Raman transitions. In a first experiment, two Raman
pulses are used to select and measure a very narrow velocity class. This method
yields to a value of the fine structure constant alpha^{-1}= 137.035 998 84
(91) with a relative uncertainty of about 6.6 ppb. More recently we use an
atomic interferometer consisting in two pairs of pi/2 pulses. We present here
the first results obtained with this method
New determination of the fine structure constant and test of the quantum electrodynamics
We report a new measurement of the ratio between the
Planck constant and the mass of atom. A new value of the
fine structure constant is deduced, with
a relative uncertainty of . Using this determination, we
obtain a theoretical value of the electron anomaly
which is in agreement with the
experimental measurement of Gabrielse
(). The comparison of these values
provides the most stringent test of the QED. Moreover, the precision is large
enough to verify for the first time the muonic and hadronic contributions to
this anomaly
Large Momentum Beamsplitter using Bloch Oscillations
The sensitivity of an inertial sensor based on an atomic interfermometer is
proportional to the velocity separation of atoms in the two arms of the
interferometer. In this paper we describe how Bloch oscillations can be used to
increase this separation and to create a large momentum transfer (LMT)
beamsplitter. We experimentally demonstrate a separation of 10 recoil
velocities. Light shifts during the acceleration introduce phase fluctuations
which can reduce the contrast of the interferometer. We precisely calculate
this effect and demonstrate that it can be significantly reduced by using a
suitable combination of LMT pulses. We finally show that this method seems to
be very promising to realize LMT beamsplitter with several 10s of recoil and a
very good efficiency
Bloch oscillations of ultracold atoms: a tool for a metrological determination of
We use Bloch oscillations in a horizontal moving standing wave to transfer a
large number of photon recoils to atoms with a high efficiency (99.5% per
cycle). By measuring the photon recoil of , using velocity selective
Raman transitions to select a subrecoil velocity class and to measure the final
accelerated velocity class, we have determined with a relative
precision of 0.4 ppm. To exploit the high momentum transfer efficiency of our
method, we are developing a vertical standing wave set-up. This will allow us
to measure better than and hence the fine structure
constant with an uncertainty close to the most accurate value coming
from the () determination
- âŠ