Sequential phonon measurements of atomic motion

2021 ◽  
Author(s):  
Atirach Ritboon ◽  
Lukáš Slodička ◽  
Radim Filip
Keyword(s):  
Cavity Qed ◽  
Quantum Fisher Information ◽  
Atomic Motion ◽  
Circuit Qed ◽  
Fock States ◽  
Fock State ◽  
Atomic Vibrations ◽  
State Generation ◽  
Available Information ◽  
Mechanical Sensing

Abstract The motion of trapped atoms plays an essential role in quantum mechanical sensing, simulations and computing. Small disturbances of atomic vibrations are still challenging to be sensitively detected. It requires a reliable coupling between individual phonons and internal electronic levels that light can readout. As available information in a few electronic levels about the phonons is limited, the coupling needs to be sequentially repeated to further harvest the remaining information. We analyze such phonon measurements on the simplest example of the force and heating sensing using motional Fock states. We prove that two sequential measurements are sufficient to reach sensitivity to force and heating for realistic Fock states and saturate the quantum Fisher information for a small amount of force or heating. It is achieved by the conventionally available Jaynes-Cummings coupling. The achieved sensitivities are found to be better than those obtained from classical states. Further enhancements are expectable when the higher Fock state generation is improved. The result opens additional applications of sequential phonon measurements of atomic motion. This measurement scheme can also be directly applied to other bosonic systems including cavity QED and circuit QED.

scholarly journals Quantum Fisher Information and Entanglement of Moving Two Two-Level Atoms under the Influence of Environmental Effects

Physics ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 131-146
Author(s):  
Syed Jamal Anwar ◽  
M. Usman ◽  
M. Ramzan ◽  
M. Khalid Khan
Keyword(s):  
Time Evolution ◽  
Fisher Information ◽  
Environmental Effects ◽  
Stark Effect ◽  
Thermal Environment ◽  
Quantum Fisher Information ◽  
Atomic Motion ◽  
Kerr Medium ◽  
Stark Effects ◽  
Non Linear

We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) of a two moving two-level atomic systems interacting with a coherent and thermal field in the presence of intrinsic decoherence (ID) and Kerr (non-linear medium) and Stark effects. The state of the entire system interacting with coherent and thermal fields is evaluated numerically under the influence of ID and Kerr (nonlinear) and Stark effects. QFI and von Neumann entropy (VNE) decrease in the presence of ID when the atomic motion is neglected. QFI and QE show an opposite response during its time evolution in the presence of a thermal environment. QFI is found to be more susceptible to ID as compared to QE in the presence of a thermal environment. The decay of QE is further damped at greater time-scales, which confirms the fact that ID heavily influences the system’s dynamics in a thermal environment. However, a periodic behavior of entanglement is observed due to atomic motion, which becomes modest under environmental effects. It is found that a non-linear Kerr medium has a prominent effect on the VNE but not on the QFI. Furthermore, it has been observed that QFI and QE decay soon under the influence of the Stark effect in the absence of atomic motion. The periodic response of QFI and VNE is observed for both the non-linear Kerr medium and the Stark effect in the presence of atomic motion. It is observed that the Stark, Kerr, ID, and thermal environment have significant effects during the time evolution of the quantum system.

Experimental resources needed to implement photon number splitting attack in quantum cryptography

2022 ◽  
Vol 19 (2) ◽  
pp. 025203
Author(s):  
S P Kulik ◽  
K S Kravtsov ◽  
S N Molotkov
Keyword(s):  
Coherent State ◽  
Quantum Key Distribution ◽  
Distribution Systems ◽  
Communication Channel ◽  
Random Phase ◽  
Photon Number ◽  
Fock States ◽  
Fock State ◽  
Experimental Parameters ◽  
Photon Number Splitting Attack

Abstract The analysis of the security of quantum key distribution systems with respect to an attack with nondemolishing measurement of the number of photons (photon number splitting—PNS attack) is carried out under the assumption that in the communication channel in each parcel there is a pure Fock state with a different number of photons, and the distribution of states by number of photons has Poisson statistics. In reality, in the communication channel in each parcel there are not individual Fock states, but a pure coherent state with a random phase—a superposition of Fock states with different numbers of photons. The paper analyzes the necessary experimental resources necessary to prepare individual Fock states with a certain number of photons from the superposition of Fock states for a PNS attack. Optical schemes for implementing such an attack are given, and estimates of experimental parameters at which a PNS attack is possible are made.

scholarly journals Feedback cooling of atomic motion in cavity QED

2006 ◽  
Vol 74 (1) ◽  
Author(s):  
Daniel A. Steck ◽  
Kurt Jacobs ◽  
Hideo Mabuchi ◽  
Salman Habib ◽  
Tanmoy Bhattacharya
Keyword(s):  
Cavity Qed ◽  
Atomic Motion

scholarly journals Topological phases of quantized light

2020 ◽  
Author(s):  
Han Cai ◽  
Da-Wei Wang
Keyword(s):  
Annihilation Operator ◽  
Research Area ◽  
Honeycomb Structure ◽  
Two Dimensions ◽  
Topological Phases ◽  
Fock States ◽  
Haldane Model ◽  
Fock State ◽  
Topological States ◽  
Coupling Strengths

Abstract Topological photonics is an emerging research area that focuses on the topological states of classical light. Here we reveal the topological phases that are intrinsic to the quantum nature of light, i.e., solely related to the quantized Fock states and the inhomogeneous coupling strengths between them. The Hamiltonian of two cavities coupled with a two-level atom is an intrinsic one-dimensional Su-Schriefer-Heeger model of Fock states. By adding another cavity, the Fock-state lattice is extended to two dimensions with a honeycomb structure, where the strain due to the inhomogeneous coupling strengths of the annihilation operator induces a Lifshitz topological phase transition between a semimetal and three band insulators within the lattice. In the semimetallic phase, the strain is equivalent to a pseudomagnetic field, which results in the quantization of the Landau levels and the valley Hall effect. We further construct an inhomogeneous Fock-state Haldane model where the topological phases can be characterized by the topological markers. With d cavities being coupled to the atom, the lattice is extended to d − 1 dimensions without an upper limit. This study demonstrates a fundamental distinction between the topological phases in quantum and classical optics and provides a novel platform for studying topological physics in dimensions higher than three.

ENTANGLEMENT GENERATION WITH GEOMETRIC OPERATIONS IN CAVITY QED

2009 ◽  
Vol 23 (13) ◽  
pp. 1619-1624
Author(s):  
GANG ZHANG ◽  
PING DONG ◽  
ZHUO-LIANG CAO
Keyword(s):  
Spontaneous Emission ◽  
Cavity Qed ◽  
Laser Power ◽  
Cavity Mode ◽  
Thermal State ◽  
Cluster State ◽  
Entanglement Generation ◽  
State Generation ◽  
One Step ◽  
Geometric Nature

We propose a one-step cluster state generation scheme via atomic cavity QED. The current scheme is insensitive to the cavity mode thermal state as well as the atomic spontaneous emission since the gate operations are independent of the cavity mode states and laser power is sufficiently weak. In addition, the needed operation is of geometric nature, so it is robust against random operation errors.

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