scholarly journals Quantum State Evolution in an Environment of Cosmological Perturbations

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 117
Author(s):  
Zbigniew Haba
Keyword(s):  
Density Matrix ◽  
Quantum State ◽  
Stochastic Equation ◽  
Wave Packets ◽  
Cosmological Perturbations ◽  
State Evolution ◽  
Tensor Perturbations ◽  
Universe Evolution ◽  
Relativistic Particles ◽  
Thermal States

We study the pure and thermal states of quantized scalar and tensor perturbations in various epochs of Universe evolution. We calculate the density matrix of non-relativistic particles in an environment of these perturbations. We show that particle’s motion can be described by a stochastic equation with a noise coming from the cosmological environment. We investigate the squeezing of Gaussian wave packets in different epochs and its impact on the noise of quantized cosmological perturbations.

Reconstructing wave packets by quantum-state holography

1999 ◽  
Vol 59 (3) ◽  
pp. 2163-2173 ◽  
Author(s):  
I. Sh. Averbukh ◽  
M. Shapiro ◽  
C. Leichtle ◽  
W. P. Schleich
Keyword(s):  
Quantum State ◽  
Wave Packets

scholarly journals Superconductor qubits hamiltonian approximations effect on quantum state evolution and control

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Javad Sharifi
Keyword(s):  
Quantum State ◽  
Charge Qubit ◽  
Gate Operation ◽  
Goal State ◽  
Expected Time ◽  
State Evolution ◽  
Angle Of Deviation ◽  
Hadamard Gate ◽  
Phase Qubit ◽  
And Control

AbstractMicrowave IQ-mixer controllers are designed for the three approximated Hamiltonians of charge, phase and flux qubits and the controllers are exerted both on approximate and precise quantum system models. The controlled qubits are for the implementation of the two quantum-gates with these three fundamental types of qubits, Quantum NOT-gate and Hadamard-gate. In the charge-qubit, for implementation of both gates, in the approximated and precise model, we observed different controlled trajectories. But fortunately, applying the controller designed for the approximated system over the precise system leads to the passing of the quantum state from the desired state sooner that the expected time. Phase-qubit and flux qubit have similar behaviour under the control system action. In both of them, the implementation of NOT-gate operation led to same trajectories which arrive at final goal state at different times. But in both of those two qubits for implementation of Hadamard-gate, desired trajectory and precise trajectory have some angle of deviation, then by exerting the approximated design controller to precise system, it caused the quantum state to approach the goal state for Hadamard gate implementation, and since the quantum state does not completely reach the goal state, we can not obtain very high gate fidelity.

scholarly journals Quantum clocks observe classical and quantum time dilation

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander R. H. Smith ◽  
Mehdi Ahmadi
Keyword(s):  
Uncertainty Relation ◽  
Proper Time ◽  
Wave Packets ◽  
Center Of Mass ◽  
Time Dilation ◽  
Conditional Probability Distribution ◽  
Quantum Time ◽  
Mass Uncertainty ◽  
Quantum Clocks ◽  
Relativistic Particles

Abstract At the intersection of quantum theory and relativity lies the possibility of a clock experiencing a superposition of proper times. We consider quantum clocks constructed from the internal degrees of relativistic particles that move through curved spacetime. The probability that one clock reads a given proper time conditioned on another clock reading a different proper time is derived. From this conditional probability distribution, it is shown that when the center-of-mass of these clocks move in localized momentum wave packets they observe classical time dilation. We then illustrate a quantum correction to the time dilation observed by a clock moving in a superposition of localized momentum wave packets that has the potential to be observed in experiment. The Helstrom-Holevo lower bound is used to derive a proper time-energy/mass uncertainty relation.

Quantum State Manipulation of Single-Photon Wave Packets

2014 ◽  
Author(s):  
Laura J. Wright ◽  
Michał Karpiński ◽  
Brian J. Smith
Keyword(s):  
Quantum State ◽  
Single Photon ◽  
Wave Packets

Experimental realization of quantum controlled teleportation of arbitrary two-qubit state via a five-qubit entangled state

2021 ◽  
Author(s):  
Xiao-Fang Liu ◽  
Dong-Fen Li ◽  
Yun-Dan Zheng ◽  
Xiao-Long Yang ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Density Matrix ◽  
Quantum State ◽  
Bell State ◽  
Third Party ◽  
Controlled Teleportation ◽  
Entangled State ◽  
Entanglement Measure ◽  
Experimental Realization ◽  
Operation Process ◽  
Photonic States

Abstract Quantum controlled teleportation is the transmission of the quantum state under the supervision of a third party. This paper presents a theoretical and experimental combination of an arbitrary two-qubit quantum controlled teleportation scheme. In the scheme, the sender Alice only needs to perform two Bell state measurements, and the receiver Bob can perform the appropriate unitary operation to reconstruct arbitrary two-qubit states under the control of the supervisor Charlie. We verified the operation process of the scheme on the IBM Quantum Experience platform and further checked the accuracy of the transmitted quantum state by performing quantum state tomography. Meanwhile, good fidelity is obtained by calculating the theoretical density matrix and the experimental density matrix. We also introduced a sequence of photonic states to analyze the possible intercept-replace-resend, intercept-measure-resend, and entanglement-measure-resend attacks on this scheme. The results proved that our scheme is highly secure.

scholarly journals Reconstruction of attosecond electron wave packets using quantum state holography

2013 ◽  
Vol 88 (3) ◽  
Author(s):  
K. Klünder ◽  
P. Johnsson ◽  
M. Swoboda ◽  
A. L’Huillier ◽  
G. Sansone ◽  
...  
Keyword(s):  
Quantum State ◽  
Wave Packets ◽  
Electron Wave

QUANTUM STATE AND SPONTANEOUS SYMMETRY BREAKING IN GRAVITY

1994 ◽  
Vol 03 (01) ◽  
pp. 191-194
Author(s):  
PEDRO F. GONZALEZ-DIAZ
Keyword(s):  
Quantum Gravity ◽  
Symmetry Breaking ◽  
Density Matrix ◽  
Spontaneous Symmetry Breaking ◽  
Quantum State ◽  
Positive Definite ◽  
General Quantum ◽  
Breaking Mechanism ◽  
Euclidean Wormholes

A spontaneous symmetry breaking mechanism is used in quantum gravity to obtain a convergent positive definite density-matrix as the most general quantum state of Euclidean wormholes.

scholarly journals Analytical solutions for cosmological perturbations in a one-component universe with shear stress

2015 ◽  
Vol 24 (08) ◽  
pp. 1550063 ◽  
Author(s):  
Matej Škovran
Keyword(s):  
Shear Stress ◽  
Energy Density ◽  
Shear Modulus ◽  
Ideal Fluid ◽  
Analytical Solutions ◽  
Elastic Solid ◽  
Explicit Solutions ◽  
Cosmological Perturbations ◽  
Flat Universe ◽  
Tensor Perturbations

We construct explicit solutions for scalar, vector and tensor perturbations in a less known setting, a flat universe filled by an isotropic elastic solid with pressure and shear modulus proportional to energy density. The solutions generalize the well-known formulas for cosmological perturbations in a universe filled by ideal fluid.

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