Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userInterferometer for force measurement by shortcut-to-adiabatic arms guiding
51
0
0.0
(
0
)
Added by
Sof\\'ia Mart\\'inez-Garaot
Publication date
2020
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We propose a compact atom interferometer to measure homogeneous constant forces guiding the arms via shortcuts to adiabatic paths. For a given sensitivity, which only depends on the space-time area of the guiding paths, the cycle time can be made fast without loosing visibility. The atom is driven by spin-dependent trapping potentials moving in opposite directions, complemented by linear and time-dependent potentials that compensate the trap acceleration. Thus the arm states are adiabatic in the moving frames, and non-adiabatic in the laboratory frame. The trapping potentials may be anharmonic, e.g. optical lattices, and the interferometric phase does not depend on the initial motional state or on the pivot point for swaying the linear potentials.
rate research
Read More
We propose a method to transfer the population and control the state of two-level and three-level atoms speeding-up Adiabatic Passage techniques while keeping their robustness versus parameter variations. The method is based on supplementing the standard laser beam setup of Adiabatic Passage methods with auxiliary steering laser pulses of orthogonal polarization. This provides a shortcut to adiabaticity driving the system along the adiabatic path defined by the standard setup.
Quantum metrology makes use of quantum mechanics to improve precision measurements and measurement sensitivities. It is usually formulated for time-independent Hamiltonians but time-dependent Hamiltonians may offer advantages, such as a $T^4$ time dependence of the Fisher information which cannot be reached with a time-independent Hamiltonian. In Optimal adaptive control for quantum metrology with time-dependent Hamiltonians (Nature Communications 8, 2017), Shengshi Pang and Andrew N. Jordan put forward a Shortcut-to-adiabaticity (STA)-like method, specifically an approach formally similar to the counterdiabatic approach, adding a control term to the original Hamiltonian to reach the upper bound of the Fisher information. We revisit this work from the point of view of STA to set the relations and differences between STA-like methods in metrology and ordinary STA. This analysis paves the way for the application of other STA-like techniques in parameter estimation. In particular we explore the use of physical unitary transformations to propose alternative time-dependent Hamiltonians which may be easier to implement in the laboratory.
We theoretically present the quantum Cram{e}r-Rao bounds (QCRB) of an SU(1,1) interferometer for Gaussian states input with and without the internal photonic losses. The phase shifts in the single arm and in the double arms are studied and the corresponding analytical expressions of quantum Fisher information with Gaussian input states are presented. Different from the traditional Mach-Zehnder interferometer, the QCRB of single arm case is slightly higher or lower than that of double arms case depending on the input states. With a fixed mean photon number and for pure Gaussian state input, the optimal sensitivity is achieved with a squeezed vacuum input in one mode and the vacuum input in the other. We compare the QCRB with the standard quantum limit and Heisenberg limit. In the case of small internal losses the QCRB can beat the standard quantum limit.
Interaction-free measurement is a surprising consequence of quantum interference, where the presence of objects can be sensed without any disturbance of the object being measured. Here we show an extension of interaction-free measurement using techniques from spatial adiabatic passage, specifically multiple reciever adiabatic passage. Due to subtle properties of the adiabatic passage, it is possible image an object without interaction between the imaging photons and the sample. The technique can be used on multiple objects in parallel, and is entirely deterministic in the adiabatic limit. Unlike more conventional interaction-free measurement schemes, this adiabatic process is driven by the symmetry of the system, and not by more usual interference effects. As such it provides an interesting alternative quantum protocol which may be applicable to photonic implementations of spatial adiabatic passage. We also show that this scheme can be used to implement a collision-free quantum routing protocol.
The measurement of weak continuous forces exerted on a mechanical oscillator is a fundamental problem in various physical experiments. It is fundamentally impeded by quantum back-action from the meter used to sense the displacement of the oscillator. In the context of interferometric displacement measurements, we here propose and demonstrate the working principle of a scheme for coherent back-action cancellation. By measuring the amplitude quadrature of the light reflected from a detuned optomechanical cavity inside which a stiff optical spring is generated, back-action can be cancelled in a narrow band of frequencies. This method provides a simple way to improve the sensitivity in experiments limited by quantum back-action without injection of squeezed light or stable homodyne readout.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
