## [answered] Atom-Light Interactions Problem Sheet 3 - Assessed Problems

Atom-Light Interactions

Problem Sheet 3 - Assessed Problems - Autumn 2016/17

To be handed in in the School Office, due 14:00 Wed 30th Novebember 2016 3.1 A two-level atom is placed in a cavity supporting a single mode of the electromagnetic field of frequency ?21 (resonant with the atom). The atom-cavity coupling

strength is h

? g. Neglect damping and radiative decay. (2) a. Assume that initially the atom is in the excited state, |2i, and the cavity is in

the ground state. Consider the basis |1, ni, |2, ni, corresponding to the atom

in states |1i, |2i, and n photons in the cavity. Calculate the quantum state of

the system as a function of time in this basis. (2) b. Under the conditions of question 2.a, calculate the probability of finding the

atom in the ground state as a function of time. (2) c. Under the conditions of question 2.a, calculate the mean value of the quadrature

operator X = a + a? as a function of time. (3) d. Assume now that initially the atom is in the superposition state |?i = ?12 (|1i + i|2i)

and the cavity is in the ground state. Calculate the quantum state of the system as a function of time in the basis |1, ni, |2, ni. (3) e. Under the conditions of question (d), calculate the mean value of the quadrature operator X = a + a? as a function of time. 3.2 Consider a system of N atoms interacting with a single mode of the electromagnetic

field (Tavis-Cummings model). We assume that the mode is resonant with the

atomic transition,

H= h

??

2 ?z,j + h

? ?a? a + h

?g X

j=1,...,N X   ?j+ a + ?j? a? . (1) j=1,???N The initial state of the system has n = 0 photons, and it is a linear combination

of quantum states with only one atom excited in state |2i. Each term in the linear

superposition corresponds to a different atom being excited (spin-wave excitation),

|?(0)i = X

j=1,...,N 1

? (|1i1 . . . |2ij . . . |1iN ) |n = 0i,

N (2) where |1ij , and |2ij correspond to atom j in levels 1 and 2, respectively.

(4) a. Calculate the quantum state of the system as a function of time (4) b. Calculate the evolution of the number of photons in the cavity ha? ai. How

does the oscillation frequency scale with the number of atoms, N ?

Solution details:
STATUS
QUALITY
Approved

This question was answered on: Sep 18, 2020 Solution~0001005346.zip (25.37 KB)

This attachment is locked

We have a ready expert answer for this paper which you can use for in-depth understanding, research editing or paraphrasing. You can buy it or order for a fresh, original and plagiarism-free copy from our tutoring website www.aceyourhomework.com (Deadline assured. Flexible pricing. TurnItIn Report provided)

##### Pay using PayPal (No PayPal account Required) or your credit card . All your purchases are securely protected by .

STATUS

QUALITY

Approved

Sep 18, 2020

EXPERT

Tutor 