Atom-light hybrid interferometer

Abstract

A new type of hybrid atom-light interferometer is demonstrated with atomic Raman amplification processes replacing the beam splitting elements in a traditional interferometer. This nonconventional interferometer involves correlated optical and atomic waves in the two arms. The correlation between atoms and light developed with the Raman process makes this interferometer different from conventional interferometers with linear beam splitters. It is observed that the high-contrast interference fringes are sensitive to the optical phase via a path change as well as the atomic phase via a magnetic field change. This new atom-light correlated hybrid interferometer is a sensitive probe of the atomic internal state and should find wide applications in precision measurement and quantum control with atoms and photons. [4]. They are widely used in precision measurement of a variety of physical quantities. Building on this foundation, nonconventional interferometers can be constructed with nonlinear processes such as wave splitting and recombination elements [5][6][7][8][9][10], as shown in the inset of Fig. 1.Different from the conventional interferometers with beam splitters, the involvement of nonlinear processes in the nonconventional interferometers allows the coupling between two waves of different types, and it can lead to interference fringes that are sensitive to different types of phase shifts. We thus use the word "hybrid" to label these interferometers involving different types of waves. In fact, hybrid interference also occurs via coherent interactions between atoms and light in phenomena such as quantum storage in electromagnetically induced transparency [11][12][13], gradient echo memory [14,15], and slow light [16][17][18][19][20]. However, the hybrid interference effects in these phenomena are in essence still of the same type as the conventional interference effect where the input wave is linearly split into a linear superposition of atom and light fields in the form of a polariton state [11,15]. On the other hand, a nonconventional SU(1,1) interferometer [5,9,10,21] utilizes parametric amplifiers as wave splitting and recombination elements and performs quite differently from the conventional linear interferometers. The name SU(1,1) comes from the nonlinear interaction Hamiltonian for the parametric process [5]:which amplifies an input signal field (â s ) and produces a correlated idler field (â i ) simultaneously. The idler field is coherent with the input field, thus realizing coherent wave splitting.One of the nonlinear processes described by Eq. (1) is the collective atomic Raman amplification process, which FIG. 1 (color online). Experimental sketch for the hybrid atomlight interferometer. A strong Raman write beam (W 1 , red) and a Stokes input field (S 0 , blue) in orthogonal polarization interact with a Λ-shaped atomic system to generate an amplified Stokes field (S 1 ) and a correlated atomic spin wave S a that stays in the atomic system. The amplified Stokes beam (S 1 ), after reflection (S 0 1...

Atom–light superposition oscillation and Ramsey-like atom–light interferometer

“…In contrast to the traditional interferometers, which are constructed with linear beam splitters for coherent splitting into a mixing of the same type of wave and are only sensitive to the phase shift of one type of wave, this new hybrid atom-light interferometer involves waves of different type and should depend on the phases of both optical and atomic waves. This is somewhat similar to an SU(1,1) type atom-light interferometer recently realized in our group [15] In this paper, we report on the first observation of Rabi-like oscillation between light and atom in a Raman process involving Rb-atoms and a demonstration of an atom-light interferometer by employing this Rabi-like oscillation effect as atom and light wave splitter and mixer. This is a Ramsey-type interferometer in the sense that a strong driving laser in π/2-pulse area creates a superposition between atom and light and after a time delay with the evolution of both atom and light, another π/2-pulse laser is applied to mix atom and light for interference.…”

Effects of losses in the atom-light hybrid SU(1,1) interferometer

“…That is, by injecting a seeded light field which is correlated with the initially prepared collective atomic excitation, the Raman scattering can be enhanced greatly, which was also realized in experiment recently [48]. Such a photon-atom interface can form an SU(1,1)-typed atom-light hybrid interferometer [49], where the atomic Raman amplification processes replacing the beam splitting elements in a traditional MZI [28]. Different from all-optical or all-atomic interferometers, the atom-light hybrid interferometers depend on both atomic and optical phases so that we can probe the atomic phases with optical interferometric techniques.…”

“…In this section, we use the above results to calculate the intermode correlations of the different Raman amplification processes of the atom-light interferometer as shown in Fig. 1(a)-(c) [49]. We also study the effects of the loss of light field and the dephasing of atomic excitation on the correlation.…”

Quantum non-demolition measurement of photon number with atom-light interferometers

“…Thus it will be difficult to separate the weak probe field from the strong coupling field and measure the weak probe field with low loss and low noise. Recently a new type of hybrid interferometers involving both atomic ensemble and light was demonstrated [25][26][27][28], and attracts lots of attention. This type of interferometers is based on Raman interaction between atoms and light, and is sensitive to both optical and atomic phase shift, so can be used to measure the atomic AC Stark phase shift induced by an optical probe field.…”