K. Salit

Bio: K. Salit is an academic researcher from Northwestern University. The author has contributed to research in topics: Dispersion (optics) & Interferometry. The author has an hindex of 12, co-authored 35 publications receiving 959 citations.

Ultrahigh enhancement in absolute and relative rotation sensing using fast and slow light

Abstract: We describe a resonator-based optical gyroscope whose sensitivity for measuring absolute rotation is enhanced via use of the anomalous dispersion characteristic of superluminal light propagation. The enhancement is given by the inverse of the group index, saturating to a bound determined by the group velocity dispersion. We also show how the offsetting effect of the concomitant broadening of the resonator linewidth may be circumvented by using an active cavity. For realistic conditions, the enhancement factor is as high as ${10}^{6}$. We also show how normal dispersion used for slow light can enhance relative rotation sensing in a specially designed Sagnac interferometer, with the enhancement given by the slowing factor.

Demonstration of a tunable-bandwidth white-light interferometer using anomalous dispersion in atomic vapor.

Abstract: Recently, the design of a white-light cavity has been proposed using negative dispersion in an intracavity medium to make the cavity resonate over a large range of frequencies and still maintain a high cavity buildup. This Letter presents the first demonstration of this effect in a free-space cavity. The negative dispersion of the intracavity medium is caused by bifrequency Raman gain in an atomic vapor cell. A significantly broad cavity response over a bandwidth greater than 20 MHz has been observed. A key application of this device would be in enhancing the sensitivity-bandwidth product of the next generation gravitational wave detectors that make use of the so-called signal-recycling mirror.

Observation of nonlinear optical interactions of ultralow levels of light in a tapered optical nanofiber embedded in a hot rubidium vapor.

Abstract: We report the observation of low-light level optical interactions in a tapered optical nanofiber (TNF) embedded in a hot rubidium vapor The small optical mode area plays a significant role in the optical properties of the hot vapor Rb-TNF system, allowing nonlinear optical interactions with nW level powers even in the presence of transit-time dephasing rates much larger than the intrinsic linewidth We demonstrate nonlinear absorption and V-type electromagnetically induced transparency with cw powers below 10 nW, comparable to the best results in any Rb-optical waveguide system The good performance and flexibility of the Rb-TNF system makes it a very promising candidate for ultralow power resonant nonlinear optical applications

Superluminal ring laser for hypersensitive sensing.

Abstract: The group velocity of light becomes superluminal in a medium with a tuned negative dispersion, using two gain peaks, for example. Inside a laser, however, the gain is constant, equaling the loss. We show here that the effective dispersion experienced by the lasing frequency is still sensitive to the spectral profile of the unsaturated gain. In particular, a dip in the gain profile leads to a superluminal group velocity for the lasing mode. The displacement sensitivity of the lasing frequency is enhanced by nearly five orders of magnitude, leading to a versatile sensor of hyper sensitivity.

Fast-light for astrophysics: super-sensitive gyroscopes and gravitational wave detectors

Abstract: We present a theoretical analysis and experimental study of the behaviour of optical cavities filled with slow- and fast-light materials, and show that the fast-light material-filled cavities, which can function as ‘white light cavities’, have properties useful for astrophysical applications such as enhancing the sensitivity-bandwidth product of gravitational wave detection and terrestrial measurement of Lense–Thirring rotation via precision gyroscopy.

Quantum repeaters based on atomic ensembles and linear optics

Abstract: The distribution of quantum states over long distances is limited by photon loss. Straightforward amplification as in classical telecommunications is not an option in quantum communication because of the no-cloning theorem. This problem could be overcome by implementing quantum repeater protocols, which create long-distance entanglement from shorter-distance entanglement via entanglement swapping. Such protocols require the capacity to create entanglement in a heralded fashion, to store it in quantum memories, and to swap it. One attractive general strategy for realizing quantum repeaters is based on the use of atomic ensembles as quantum memories, in combination with linear optical techniques and photon counting to perform all required operations. Here the theoretical and experimental status quo of this very active field are reviewed. The potentials of different approaches are compared quantitatively, with a focus on the most immediate goal of outperforming the direct transmission of photons.

Quantum repeaters based on atomic ensembles and linear optics

Abstract: The distribution of quantum states over long distances is limited by photon loss. Straightforward amplification as in classical telecommunications is not an option in quantum communication because of the no-cloning theorem. This problem could be overcome by implementing quantum repeater protocols, which create long-distance entanglement from shorter-distance entanglement via entanglement swapping. Such protocols require the capacity to create entanglement in a heralded fashion, to store it in quantum memories, and to swap it. One attractive general strategy for realizing quantum repeaters is based on the use of atomic ensembles as quantum memories, in combination with linear optical techniques and photon counting to perform all required operations. Here we review the theoretical and experimental status quo of this very active field. We compare the potential of different approaches quantitatively, with a focus on the most immediate goal of outperforming the direct transmission of photons.

ACM SIGCOMM computer communication review

Abstract: At some point in the future, how far out we do not exactly know, wireless access to the Internet will outstrip all other forms of access bringing the freedom of mobility to the way we access the we...

Quantum simulations and many-body physics with light

Abstract: In this review we discuss the works in the area of quantum simulation and many-body physics with light, from the early proposals on equilibrium models to the more recent works in driven dissipative platforms. We start by describing the founding works on Jaynes-Cummings-Hubbard model and the corresponding photon-blockade induced Mott transitions and continue by discussing the proposals to simulate effective spin models and fractional quantum Hall states in coupled resonator arrays (CRAs). We also analyse the recent efforts to study out-of-equilibrium many-body effects using driven CRAs, including the predictions for photon fermionisation and crystallisation in driven rings of CRAs as well as other dynamical and transient phenomena. We try to summarise some of the relatively recent results predicting exotic phases such as super-solidity and Majorana like modes and then shift our attention to developments involving 1D nonlinear slow light setups. There the simulation of strongly correlated phases characterising Tonks-Girardeau gases, Luttinger liquids, and interacting relativistic fermionic models is described. We review the major theory results and also briefly outline recent developments in ongoing experimental efforts involving different platforms in circuit QED, photonic crystals and nanophotonic fibres interfaced with cold atoms.

Fundamentals and Applications of Slow Light

Abstract: "Slow and fast light" constitute a broad class of science and technology that can dramatically change the group index of a medium over a certain wavelength range. This thesis is composed of studies regarding both fundamental aspects and applications of slow light. The thesis starts with some discussion on two fundamental questions. The first one is how much momentum a photon carries within a slow-light medium, and what kind of force is experienced by a slow-light medium when a photon enters or leaves it. The second issue is how the noise properties of an optical field change as it propagates through a slow-light medium. The second part of the thesis deals with the applications of slow light for tunable time delays. For such applications, one of the key figures of merit is the maximum fractional delay that a slow-light element can achieve. I first present a method with experimental demonstrations for improving the maximum fractional delay using a multiple-gain-line medium. Second, I present a design with experimental demonstration for how to achieve simultaneous tunable delay and advancement using slow and fast light in a single module. I then propose a design of a digitally tunable module using channelized slow light, which can be useful for optical packet delays, etc. The third part of the thesis studies the use of slow light to enhance the performance of spectroscopic interferometers. I start with the derivation of the spectral sensitivity of two-beam and multiple-beam interferometers with slow-light media incorporated in them. I show both theoretically and experimentally that the spectral sensitivity is proportional to the group index of the medium inside the interferometers. Second, I propose and demonstrate experimentally a new type of Fourier-transform interferometer using tunable slow light. I then analyze the performance of three types of slow-light media for interferometry applications. Lastly, I present a design of an on-chip slow-light spectrometer as well as some studies on slow-light waveguides using photonic crystal structures.