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We propose a new method to overcome quantum back-action in a measurement process using oscillators. An optical oscillator is used as a meter to measure the parameters of another open oscillator. The optical oscillator is synthesized such that the optical restoring force counters any perturbations induced by the quantum back-action phenomena. As a result, it is shown that the quantum back-action in continuous measurement is suppressed in the low frequency regime i.e., for frequencies much smaller than the resonance frequency of the open oscillator. As the meter plays the role of measuring parameters as well as suppressing the quantum back-action, we call it as quantum back-action nullifying meter. As an application of this method, synthesis of quantum back-action nullifying optical oscillator for suppressing radiation pressure force noise in linear and non-linear optomechanics is described., 6 pages, 1 figure

Continuous measurement of position in optical interferometer is limited by standard quantum limit. In this work we propose a new method to go beyond the standard quantum limit by using quantum optical restoring force.

This Letter proposes a new method to eliminate the quantum radiation pressure force noise in optomechanics at frequencies much smaller than the resonance frequency of the optomechanical mirror. With no radiation pressure force noise, the shot noise and thermal noise together determine the total noise in the system. The force sensitivity of the optomechanical cavity is improved beyond standard quantum limit at frequencies much smaller than the resonance frequency of the mechanical oscillator. Finally, optimum optomechanical cavity design parameters for attaining the best sensitivity are discussed.

This publisher’s note contains corrections to Opt. Lett. 45, 1256 (2020)OPLEDP0146-959210.1364/OL.385092.

We propose an interferometry technique, by using electromagnetically induced transparency phenomena, for measuring classical force. The classical force is estimated by measuring the phase at the output of the interferometer. The proposed measurement mechanism satisfies quantum non-demolition measurement conditions leading to back-action evasion. We further derive the sufficient condition under which the thermal noise in the interferometer is negligible. With no back-action noise and no thermal noise, the sensitivity of this technique is limited by shot noise only., Comment: 6 pages

Coherent quantum noise cancellation (CQNC) method is used to beat standard quantum limit (SQL) for improving the per-formance of quantum optomechanical gyroscopes. The protocol for realizing CQNC is achieved by constructing an effectivenegative mass mechanical oscillator, which is simulated by an ancillary cavity. This oscillator shows an antiresponse relativeto that of a real mechanical oscillator. Thus, the optomechanical back-action noise is counteracted or restrained, and we couldincrease our signal by increasing the coupling strength without increasing the noise.

Destructive and constructive interference in the Autler–Townes three-level systems is studied in the dressed state basis. The dependence of the interference on the spontaneous emission and dephasing reservoirs is analyzed. The strong field correlates or anti-correlates the random phase caused by the reservoirs. The correlation reduces and the anti-correlation enhances the absorption. Each of the interference pathways is formed by two processes, stimulated absorption and spontaneous emission. The interference effect can be neglected if the Rabi frequency of the strong field is larger than the decay rates.

We consider an opto-mechanical effect that is related to the appearance of additional optical phase due to motion of an ultra-dispersive medium, the enhanced Fizeau effect. We have theoretically shown that the enhanced Fizeau effect on a single atom in a cavity can be observed. It has been shown that the change of phase is sensitive to the mechanical motion and can be applied to measurement of possible displacements as small as cm Hz. One of application can be the detection of weak forces exerted on a single atom.

In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

It is well known that in a three-level lambda system, spontaneous emission decay rate on the lasing transition must be smaller than or equal to the decay rate on the driving transition in order to observe LWI. Since spontaneous emission rate is proportional to cube of the corresponding transition frequency, satisfying the above condition requires the frequency of lasing transition to be smaller than the driving transitions frequency. In other words, according to this condition, frequency upconversion is not possible with LWI. The main theme of this article is to suggest the possibilty of frequency upconversion in LWI by overcoming the condition described above.

In this article, we present an application of the optomechanical cavities for absolute rotation detection. Two optomechanical cavities, one in each arm, are placed in a Michelson interferometer. The interferometer is placed on a rotating table and is moved with a uniform velocity of with respect to the rotating table. The Coriolis force acting on the interferometer changes the length of the optomechanical cavity in one arm, while the length of the optomechanical cavity in the other arm is not changed. The phase shift corresponding to the change in the optomechanical cavity length is measured at the interferometer output to estimate the angular velocity of the absolute rotation. An analytic expression for the minimum detectable rotation rate corresponding to the standard quantum limit of measurable Coriolis force in the interferometer is derived. Squeezing technique is discussed to improve the rotation detection sensitivity by a factor of at 0 K temperature, where and are the damping rate and angular frequency of the mechanical oscillator. The temperature dependence of the rotation detection sensitivity is studied.

We propose an experiment to demonstrate a strong coherent backward and forward microwave generation using forward-propagating optical fields only. This is achieved by applying laser fields to an ultradispersive medium with properly chosen detunings and/or Rabi frequencies to excite a spin coherence that generates a forward- or backward-propagating microwave. Applications to coherent scattering and remote sensing are discussed.

We consider a moving ultra-dispersive medium and demonstrate the enhanced Fizeau effect due to dragging the light. We have shown that the enhanced Fizeau effect on a single atom in a cavity can be observed. It has been shown that the change of phase is sensitive to the motion the speed of the order of 10 −15 cm/Hz 1/2 and for possible displacements as small as 10 −17 cm/Hz 1/2 . One of application can be the detection of weak forces exerted on a single atom. In particular, the Coriolis force as small as 10 −42 N/Hz 1/2 can be detected that would provide opportunity to detect rotation with sensitivity 10 −17 s −1 Hz −1/2 .

Article discussing research on the controllable enhanced dragging of light in ultradispersive media.

Stark splitting and quantum interference effects in the absorption spectrum of a probe field in coherently driven closed upper coupled three level atomic schemes ( and upper-cascade), which are created by a strong driving field are studied using the dressed state representation. In the dressed representation, the absorption due to the Stark splitting can be separated from the absorption due to the interference effects. We explicitly show the presence of both destructive and constructive interference in upper coupled three level atomic schemes. The interference in these atomic schemes is due to the coupling of the two dressed states by the same vacuum modes and the probe. We show that the dephasing rates can change the nature of the interference from constructive to destructive and vice versa, resulting in increased or decreased resonant absorption of the probe field.

In this article, we describe controlling the optomechanically induced transparency (OMIT) phenomena through rotation. An optomechanical cavity, which is coupled to a weak probe field and to a strong drive field, is placed along the diameter of a rotating table. When the table rotates, the centrifugal force due to rotation changes the length of the optomechanical cavity because of which the transparency window in OMIT disappears. We further point out that OMIT can be recovered by shifting both the drive and probe frequencies simultaneously. We derived an analytic parameter to estimate the minimum angular velocity that can effect OMIT for a given optomechanical cavity. In other words, we describe turning on and turning off OMIT by controlling the rotation rate.

We consider optomechanical effects that are related to the appearance of an additional optical phase due to the motion of an ultradispersive medium and the rotational Doppler effect for light. We have theoretically shown that the enhanced Fizeau effect on atoms in a cavity can be observed and the change of phase is sensitive to the mechanical motion. These two effects can be applied to the measurement of rotations as small as 10−17 s−1 Hz1/2. It is worth noting here that the measurement of rotation is not related to Sagnac interferometry.

A four-level atomic system interacting with two strong drive fields and a weak probe field has been studied. We demonstrate that the group velocity of probe field can be controlled to switch from subluminal to superluminal or even negative values around the probe resonance without any significant absorption. The basic idea is to create a gain with slow light on the probe beam resonance with one drive field while the other drive creates a dip in the gain profile of probe leading to superluminal and negative group velocities. A simple switching from slow light to negative group velocity light can be obtained by changing the relative intensities of drive fields. We also describe a control to tune the position of slow light frequency continuously simply by adjusting the relative intensities of both the driving fields.