This work introduces a quantum-enhanced torque sensing methodology utilizing coherent quantum noise cancellation (CQNC) within a hybrid optomechanical architecture termed the auxiliary coupled Laguerre-Gaussian (LG) optorotational cavity. The setup comprises a primary rotational cavity supporting an LG optical mode interacting with a rotating mirror, alongside an auxiliary op- tical resonator embedding an effective two-level atomic ensemble that emulates a negative mass oscillator. Photon-hopping mediated inter-cavity coupling facilitates phase-coherent energy exchange, enabling engineered interference pathways that mitigate quantum back-action noise-the principal quantum limit in precision torque transduction. Through analytical derivation and spectral response analysis, we demonstrate that this configuration facilitates torque sensitivity surpassing the standard quantum limit (SQL) across a wide frequency band. The integration of heterodyne CQNC offers a tunable detection bandwidth, positioning the system as a strong candidate for high-precision metrology and quantum-limited force sensing applications. These results pave the way for developing advanced quantum torque sensors, thereby furthering both theoretical research and practical measurement methodologies.
This work introduces a quantum-enhanced torque sensing methodology utilizing coherent quantum noise cancellation (CQNC) within a hybrid optomechanical architecture termed the auxiliary coupled Laguerre-Gaussian (LG) optorotational cavity. The setup comprises a primary rotational cavity supporting an LG optical mode interacting with a rotating mirror, alongside an auxiliary op- tical resonator embedding an effective two-level atomic ensemble that emulates a negative mass oscillator. Photon-hopping mediated inter-cavity coupling facilitates phase-coherent energy exchange, enabling engineered interference pathways that mitigate quantum back-action noise-the principal quantum limit in precision torque transduction. Through analytical derivation and spectral response analysis, we demonstrate that this configuration facilitates torque sensitivity surpassing the standard quantum limit (SQL) across a wide frequency band. The integration of heterodyne CQNC offers a tunable detection bandwidth, positioning the system as a strong candidate for high-precision metrology and quantum-limited force sensing applications. These results pave the way for developing advanced quantum torque sensors, thereby furthering both theoretical research and practical measurement methodologies.
We investigate the reduction of measurement-added noise in force sensing by analyzing its power spectral density (PSD) within a hybrid optomechanical system. The setup is comprised of an optomechanical cavity equipped with a movable mirror which acts as the mechanical oscillator, a stationary semi-transparent mirror, a superconducting qubit, and an optical parametric amplifier (OPA). By utilizing the concept of coherent quantum noise cancellation (CQNC), we derive the conditions necessary for complete cancellation of back-action force, thereby enhancing force sensitivity. Furthermore, with the gradual increase in the OPA pump gains, we suppress the sensitivity beyond the standard quantum limit (SQL) at a lower value of laser power. The removal of back-action noise, along with the reduction of shot noise, improves force detection capabilities, thereby surpassing the standard quantum limit associated with weak force detection.
We theoretically study how quantum measurement noise can be engineered in a hybrid cavitymagnomechanical platform for precision force sensing. The proposed configuration consists of a driven optomechanical cavity, with a movable mirror on one side plus a fixed semi-transparent mirror on the other side, coupled to a magnon mode, with an OPA placed inside the cavity. We show that the magnon mediated dynamics reshapes the added-noise spectrum leading to improved sensitivity compared to a conventional optomechanical sensor. In particular, by satisfying the coherent quantum noise cancellation (CQNC) criterion, radiation-pressure back-action can be fully suppressed. In addition, a larger OPA pump gain permits operation beyond the standard quantum limit at substantially reduced laser power, thereby mitigating power-related constraints without sacrificing performance. These combined advantages provide a practical pathway to below-SQL weak force detection and can outperform existing approaches based on squeezing in magnomechanics.
We investigate the reduction of measurement-added noise in force sensing by analyzing its power spectral density (PSD) within a hybrid optomechanical system. The setup comprises of an optomechanical cavity equipped with a movable mirror which acts as the mechanical oscillator, a stationary semi-transparent mirror, a superconducting qubit, and an optical parametric amplifier (OPA). By utilizing the concept of coherent quantum noise cancellation (CQNC), we derive the conditions necessary for complete cancellation of back-action force, thereby enhancing force sensitivity. Furthermore, with the gradual increase in the OPA pump gains, we suppress the sensitivity beyond the standard quantum limit (SQL) at a lower value of laser power. The removal of back-action noise, along with the reduction of shot noise, improves force detection capabilities, thereby surpassing the standard quantum limit associated with weak force detection.
The weak force sensing based on a coherent quantum noise cancellation (CQNC) scheme is presented in a hybrid cavity optomechanical system containing a trapped ensemble of ultracold atoms and an optical parametric amplifier (OPA). In the proposed system, the back-action noise can be completely eliminated at all frequencies and through the proper choice of the OPA parameters, and the noise spectral density can also be reduced at lower frequencies. This leads to a significant enhancement in the sensitivity of the cavity optomechanical weak force sensor, and the noise spectral density also surpasses the standard quantum limit (SQL) even for the small input power at the lower detection frequency. Furthermore, the experimental feasibility of this scheme is also briefly discussed. This study can be used for the realization of a force sensor based on hybrid cavity optomechanical systems and for the coherent quantum control in macroscopic systems.
In this paper we propose an experimentally viable scheme to enhance the sensitivity of force detection in a hybrid optomechanical setup assisted by squeezed vacuum injection, beyond the standard quantum limit (SQL). The scheme is based on a combination of the coherent quantum noise cancellation (CQNC) strategy with a variational homodyne detection of the cavity output spectrum in which the phase of the local oscillator is optimized. In CQNC, realizing a negative-mass oscillator in the system leads to exact cancellation of the backaction noise from the mechanics due to destructive quantum interference. Squeezed vacuum injection enhances this cancellation and allows sub-SQL sensitivity to be reached in a wide frequency band and at much lower input laser powers. We show here that the adoption of variational homodyne readout enables us to enhance this noise cancellation up to 40dB compared to the standard case of detection of the optical output phase quadrature, leading to a remarkable force sensitivity of the order of ${10}^{\ensuremath{-}19}\phantom{\rule{0.28em}{0ex}}\mathrm{N}/\sqrt{\mathrm{Hz}}$, about 70 enhancement compared to the standard case. Moreover, we show that at nonzero cavity detuning, the signal response can be amplified at a level three to five times larger than that in the standard case without variational homodyne readout, improving the signal-to-noise ratio. Finally, the variational readout CQNC developed in this paper may be applied to other optomechanical-like platforms such as levitated systems and multimode optomechanical arrays or crystals as well as Josephson-based optomechanical systems.
We theoretically investigate quantum measurement noise in a hybrid optomechanical system, focusing on radiation pressure back action and its impact on force sensing. The setup consists of an optomechanical cavity with a movable mirror, a fixed semi transparent mirror, an ensemble of quantum dots (QD) coupled to the cavity mode, and an intracavity optical parametric amplifier (OPA). We show how the QD induced response, together with the system nonlinearity, modifies the noise spectral density and thereby improves the force measurement sensitivity. In this setup, coherent quantum noise cancellation (CQNC) can completely remove the back action noise. In addition, increasing the OPA pump gain enables sensitivity beyond the standard quantum limit (SQL) at reduced laser power. These combined effects allow weak force sensing beyond the SQL.