Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Quantum and atom optics > Definitions > Flashcards

Definitions Flashcards

(56 cards)

Start Studying
1
Q

What is a property of observables?

A

All observables are hermitian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do we go from a position representation to a momentum representation?

A

By setting θ = π/2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do we quantise an electromagnetic field

A

By associating each mode with a quantum harmonic oscillator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are number states

A

They are eigenstates of the number operator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are coherent states

A

The most classical states for the quantised electromagnetic field. Coherent states are over-complete.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is over-completeness?

A

States that obey the integral closure relation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the vacuum state?

A

The vacuum state is a coherent state.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens the more classical a state becomes?

A

The more classical a state becomes the less the fluctuations matter.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Compare number states and coherent states

A

Number states are highly non classical whereas coherent states are highly classical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is normal ordering

A

Placing all the creation operators to the left of the annihilation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a pure state?

A

A single state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the phase difference between r and t?

A

π/2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is anti-bunching?

A

When we put one photon in each input but the output is in the same arm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Homodyne detection?

A

A beamsplitter with a local oscillator. Where the signal and local oscillator have the same frequency. The detection relies on amplification which is achieved through the mixing of signals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are some properties of photons?

A

Photons can be reflected and diffracted. The light waves can interfere. Coherent light can be produced by lasers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are some properties of atoms?

A

Atoms can be reflected and experience bragg diffraction. Atom beams/single atoms can interfere. They can be cooled, confined and tuned into coherent atom lasers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do dipole traps operate?

A

Dipole traps operate at large detunings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a shift in potential known as?

A

Is known as AC stark effect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what does light scattering result in?

A

Light scattering results in atom cooling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How can we trap atoms?

A

Using the dipole force.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is red detuning?

A

When ẟ < 0 atoms assemble where the light field intensity is highest. We get high-field seekers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is blue detuning?

A

When ẟ > 0 atoms assemble where the light field intensity is lowest. We get low field-seekers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe light in an atomic vapour?

Study These Flashcards
A

Can be absorbed - amplitude decreases
Can be refracted - phase changes
Can be slowed - phase changes with frequency

24
Q

What are the different parts of the refractive index responsible for?

Study These Flashcards
A

The real part is responsible for the phase change whereas the imaginary part is responsible for the amplitude change (absorption).

25
What are the two terms of the dipole force?
First term - dipole/gradient force second term - scattering force.
26
What is the shape of the absorption profile>
It is lorentzian with strongest absorption of ẟ = 0 and a FWHM = γ
27
What are the three processes ...?
Absorption - transfers ħk momentum to the atom Stimulated emission - changes atom's momentum by -ħk spontaneous emission - no net transfer of momentum
28
What is co- and counter-propagating?
counter-propagating - atom moving towards light -> use red detuning co-propagating - atom moving in the same direction as light -> use blue detuning
29
What is chirp cooling?
Chirp cooling involves adjusting the laser frequency ω to stay in resonance with the atoms.
30
What is Zeeman cooling?
Zeeman cooling involves adjusting the resonance frequency ω0 by applying an external magnetic field in order for the zeeman shift to compensates the doppler shift.
31
What happens if our laser is far off resonance
The beam has far less effect
32
What property changes with each absorption-emission cycle?
The velocity. It is reduced.
33
Why do we have two temperature limits?
Because during spontaneous emission recoil heats the atoms.
34
What is the recoil temperature?
The fundamental limit below which atoms cannot be cooled with optical techniques.
35
What is the doppler temperature?
The doppler temperature arises from the balance between doppler cooling and recoil heating. It can be overcome by optical cooling techniques.
36
How can we build a magneto-optical trap?
1. A magnetic system - using helmholtz coils 2. An optical system - to trap and cool the light 3. A vacuum system
37
Describe the magnetic system in a MOT?
The magnetic energy levels require a restoring force which is the scattering force that always points towards the centre of the trap.
38
How do we drive transitions in a MOT?
By using red-detuning to drive mf = -1
39
Describe the three systems used in dipole traps?
1. Ray optics - for particles larger than the laser wavelength 2. Electric dipole approximation - for particles on the order of the laser wavelength 3. AC stark shift - for particles smaller than the laser wavelength.
40
What does the interaction strength depend on?
The size of the dipole.
41
What does the Rabi frequency describe?
It characterises the strength of the dipole interaction.
42
What do the populations describe?
The diagonals or populations in the atomic density operator describe the probability of a system
43
What do the coherences describe?
The off-diagonals or coherences in the atomic density operator describe the transition between atomic states.
44
What is electromagnetically-induced transparency?
A system where if both transitions are driven atoms cannot absorb light and when on resonance atoms are transparent.
45
What is the EIT process?
1. Light drives transitions between |c> and |e> 2. eventually all atoms will be in state |n> 3. Light can no longer be absorbed
46
Describe sisyphus cooling?
σ+ photon is absorbed by an atom in state mF = -1/2. In an excited state it has 50% probability of decaying into mF = 1/2. σ+ photon is absorbed by an atom in state mF = +1/2. In an excited state it has 100% probability of decaying into mF = 1/2.
47
At what rate do the atoms move from the ground state to the excited state?
At a rate given by the Rabi frequency.
48
What is a π-pulse?
A pulse of π/Ω transfers the population from the ground to excited state.
49
What is a π/2 pulse?
A pulse of π/2/Ω puts atoms that were initially in the ground state into an equal super position of ground & excited states.
50
When do we get the saturation intensity?
When the excited state population in the steady state reaches half its maximum.
51
What are dressed states?
Dressed states are the combination of the atom and the light field. Defining a new set of eigenvalues.
52
What are partially dressed states?
Coupling state |c> and non-coupling state |n>.
53
What is the schrodinger picture?
Operators are time independent and states are time dependent.
54
What is heisenberg picture?
Operators are time dependent and states are time independent.
55
What are the dynamics the JC model?
Consider -> zero detuning -> atom initially in |e> -> field initially in |n> -> initial joint state |i> = |e>|n> -> initial energy Ei = 1/2ħw0 + nħw
56
What does a JC system undergo?
Rabi oscillations. These persist even when n = 0 and are known as vacuum rabi oscillations.

Quantum and atom optics (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions