Banca de DEFESA: Miguel Citeli de Freitas

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Miguel Citeli de Freitas
DATE: 14/09/2023
TIME: 10:00
LOCAL: Auditório do IF
TITLE:

Squeezing and non-Gaussianity of coherent phase states

 

KEY WORDS:

Coherent phase state. squeezing. Gaussianity. Wigner function.

PAGES: 48
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

One of the main attempts to describe the phase of quantum systems was proposed by Lerner, Huang and Walters in 1970 with the introduction of coherent phase states |ε⟩ = p 1 − |ε| 2 P∞ n=0 ε n |n⟩, where |n⟩ are the Fock states and ε = |ε|e iφ, with |ε| < 1 and φ ∈ [0, 2π). The states |ε⟩ were named by Shapiro, Shepard and Wong in 1990 due to their similarity with the Glauber-Sudarshan coherent state, differing only in the absence of the factor 1/ √ n! in its definition, |α⟩ = exp − 1 2 |α| 2 P∞ n=0 α n √ n! |n⟩. Since most works on phase are dedicated to studying properties of the number and phase operators (ˆn, φˆ), we chose to focus our research on the characteristics associated with the position and moment operators (ˆx, pˆ), initially calculating mean values and variances. We observe that there is a strong squeezing of the position (momentum) when the phase is equal to π/2 (0), although this is still smaller than the squeezing suffered by the squeezed vacuum state. We noticed that the mixed analogue of the pure state |ε⟩, described by the statistical operator ˆρ = (1 − |ε| 2 ) P∞ n=0 |ε| 2n|n⟩⟨n|, has a Gaussian density matrix ⟨x|ρˆ|x⟩, even though the probability density |ψε(x)| 2 is not. For this reason, we investigated in detail different measures of non-Gaussianity of coherent phase states. Finally, we calculated the Wigner function of |ε⟩ and saw how Gaussianity is easily lost with small variations of φ when ε is close to 1.

COMMITTEE MEMBERS:
Interno - 1108259 - CAIO CESAR HOLANDA RIBEIRO
Externo à Instituição - MATHEUS BARBOSA DE ALCÂNTARA HOROVITS - IFB
Interno - 2650530 - SERGIO COSTA ULHOA
Presidente - 1218902 - VIKTOR DODONOV