Study Of Light-atom Quantum Accelerometer

The precision measurement of acceleration is widely used in many fields.The basic working principle of the accelerometer is to measure the displacement of the installed test body.High sensitivity displacement measurement can be achieved using capacitive,piezoelectric,piezoresistive or optical methods.The traditional accelerometer has a very high resolution for gravity measurement or seismic measurement,and the accuracy can reach fg/?Hz.However,the acceleration up to the measurement frequency is far lower than KHz,so it is often ineffective for the measurement of fast moving piezoelectric devices.For example,the ability to maintain very high resolution over a large bandwidth of tens of kilohertz would be of great interest in applications such as inertial navigation of fast-moving objects.The reason for this difficulty is that achieving a specific acceleration resolution over a given bandwidth range has a specific tradeoff.The larger the bandwidth required for the acceleration sensor,the more challenging it is to achieve the displacement resolution required for the same sensitivity.At the same time,the accelerometer with large bandwidth has no advantage in the measurement of low frequency acceleration,which also increases the cost of acceleration measurement.Currently,state-of-the-art acceleration calibration uses well-designed and instrumented shakers that are moved by acceleration and are measured using laser interferometry.The mechanical properties of the vibrator on the vibration table,such as stiffness(mass and resonant frequency)and quality factors,also play an important role in the sensing limit and transduction of acceleration in displacement measurement.In optomechanical systems,the actual displacement sensitivity can reach the standard quantum limit only under the ideal system(no loss).In particular,for high performance acceleration sensors at higher temperatures,a large oscillator mass and a high mass factor will be required to reduce the impact of classical thermal noise,which increases the manufacturing difficulty and performance improvement of the accelerometer.In this paper,we introduce and analyze the method of constructing high-precision accelerometer with memory assist and optical and atomic hybrid interferometer,aiming at the current situation that the accuracy of accelerometer is difficult to break through the standard quantum limit and the bandwidth of accelerometer cannot be changed to achieve the optimal measurement.We made the following theoretical design:1.Cold atoms can be trapped in magneto-optical traps.When the trapped optical channel is closed,the atom is temporarily suspended due to inertia,which can be regarded as the test mass that produces relative displacement in the non-inertial reference frame.For accelerometers,the main source of measurement error is the thermal Brownian motion,including the effect of the test mass and the reflection end mirror.The sensitivity of the accelerometer can be increased by replacing the test mass with cold atoms and using the memory assist for optical path reversal,which can avoid the influence of thermal Brownian noise.2.In quantum storage,the memory light needs to be written and read.In this case,the storage time can be used as a controllable measurement variable.The sensing of acceleration must be completed within one memory cycle,which means that the storage frequency is the upper frequency of the sensing acceleration.By changing the storage time of signal light,the measurement frequency band of acceleration can be effectively changed,and the conversion between different bandwidths can be realized,which is helpful to find the corresponding optimal sensitivity under the specific frequency band of measurement.