Complete control of the quantum state with oscillating magnetic field

a.wojciechowski, wt., 01/14/2025 - 13:06

PRELEGENT:

MSc. Arash Dezhang Fard

DataSeminarium:

2025-01-20

AfiliacjaPrelegenta:

Zakład Fotoniki IFMS UJ

AbstraktSeminarium:

Quantum-state engineering involves the deliberate manipulation and control

over quantum-states to generate systems with specific quantum properties.

However, in order to develop robust schemes of the manipulations, one

must gain precise knowledge about the states. In this task, quantum-state

tomography plays a key role [1, 2].

Here, we present our experimental studies on the reconstruction of the

collective density matrix of the ground-state of 87Rb. The heart of our experimental

setup is the room-temperature atomic vapor, which has two hyperfine

ground states with F = 1, 2 (F is total angular momentum). Reconstruction

of the state in the F = 2 manifold is one of challenges due to the energy

degeneracy of the magnetic sublevels splitting. However, to address this issue

we propose an oscillating magnetic field inducing both linear and and

quadratic Zeeman effect at not-too strong fields (B ≤ 25 Gauss). Interestingly,

application of oscillating magnetic field allows us to cancel the linear

effect contribution inducing only quadratic coupling. We demonstrate the

conversion from orientation of the atomic polarization to alignment, which

indicates the ability to fully control the ground state of atoms [3].

References

[1] M. Kopciuch and S. Pustelny, Optical reconstruction of the collective density

matrix of a qutrit, Phys. Rev. A 106, 022406 (2022).

[2] M. Piotrak, M. Kopciuch, A. D. Fard, M. Smolis, S. Pustelny, and K. Korzekwa,

Perfect quantum protractors, Quantum 8, 1459 (2024).

[3] A. D. Fard, M. Kopciuch, Y. Sun, P. W lodarczyk, and S. Pustelny, Isolating

pure quadratic zeeman splitting (2024), arXiv:2412.07610 [quant-ph].

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