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Electromagnetically Induced Transparency and Slow Light. Joyce Poon Oct. 29, 2003. Outline. What is EIT? Overview of light-atom interaction EIT physics: derivation, experimental results Dispersive properties and slow light Other interesting effects. EIT.

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Presentation Transcript
  • What is EIT?
  • Overview of light-atom interaction
  • EIT physics: derivation, experimental results
  • Dispersive properties and slow light
  • Other interesting effects
  • Proposed independently by Kocharovskaya and Khanin (Inst. of Applied Physics, Russia) in 1988, and Stephen E. Harris (Stanford) in 1989
  • Electromagnetically Induced Transparency is

“a technique for eliminating the effect of a medium on a propagating beam of electromagnetic radiation.”

  • Renders an opaque medium transparent
  • The physical basis for EIT is

Coherent Population Trapping (CPT)

quick review of light matter interaction



Quick Review of Light-Matter Interaction

2 level atom, semiclassical picture


Unperturbed part:


Rabi Frequency:

2 level atom semiclassical picture
2 Level Atom, Semiclassical Picture

Solve the system of equations using TDPT.


“interaction picture”

After RWA:

Solution: (no detuning)

sine and cosine

Probability amplitudes:


physics of eit






Physics of EIT

Consider lambda system (3 level atom):



Nominally, medium absorbs the probe (resonant transition).

In EIT, medium can be transparent to probe beam by tuning the coupling beam (for a certain initial state of atoms).

Quantum interference of the transition probabilities between 2  3 and 1  3

some math
Some Math

Unperturbed Hamiltonian:




2 Rabi frequencies corresponding to the probe and coupling

Neglected damping, decay, broadening

transparency solutions
Transparency Solutions

Consider various initial conditions:


atom is not absorbing for all t.

More typical EIT situation:


for all t

“un-coupled/dark state”

population trapped in lower states

A coherent superposition is required (phase is very important):


for all t

“coupled state”

adiabatic preparation
Adiabatic Preparation

How to prepare coherent state?

  • Assume initially, the population is in the ground state |1 .
  • Turn on coupling (probe off, p=0), this is an eigenstate!
  • The population is all in the ground state |1 .
  • Then increase both the control and probe slowly (adiabatically) and the atom will remain in the eigenstate.

Condition for adiabatic preparation:

experimental results
Experimental Results

Transmission vs. Probe Detuning

First demonstration by K.J. Boller, A. Imamoglu, and S.E. Harris in Strontium (Sr) vapour (1991)

Energy Diagram

Transmission at resonance changed from exp(-20) to exp(-1) !

Transmission of probe laser. Top: No coupling laser, Bottom: With coupling

dispersion and slow light
Dispersion and Slow Light

Refractive index changes rapidly with frequency near resonance slow group velocity

Normally, this is an absorbing region of the spectrum, but with EIT, the medium is transparent to the pulse.

To find group velocity, calculate susceptibility:

experimental demonstration
Experimental Demonstration

Harris et al. (1992): Pb vapour, c/vg = 250

Hau et al. (1999): Bose-Einstein condensate of Na, T<435nK

small Doppler broadening  narrow linewidth more delay

at 40nK, vg= 17m/s!!! c/vg~107

more recent developments
More Recent Developments
  • Hot Gas: Scully et al. (1999): 360K Rb, vg=90m/s
    • Rabi frequency of coupling field must be much larger than the Doppler linewidth and homogeneous broadening of probe and coupling transitions

Room Temp.: Budker et al. (1999): Rb vapour, vg ~ 8m/s

In solids: Turukhin et al. (2002): Pr doped Y2SiO5, 5K, vg=45m/s

Praseodymium (59): rare earth

  • Very intense beams required: coupling=77W/cm2, probe=5.5W/cm2

Delays for various probe detunings in Pr doped Y2 SiO5

other applications of eit
Other Applications of EIT
  • Lasers without inversion
    • No absorption into |3, no need for stimulated emission to counteract stimulated absorption
    • Get amplification at probe frequency
  • Nonlinear optics
    • Optical nonlinearity strongest at resonance
    • Now resonant wavelength is not attenuated
    • Enhanced Kerr nonlinearity, nonlinear frequency conversion
  • EIT in semiconductors (LWI)
    • Engineer transition energy levels (band engineering) in quantum wells/wires/dots

  • S. Alam. Lasers without Inversion and Electromagnetically Induced Transparency. Washington: SPIE, 1999.
  • S.E. Harris. Electromagnetically Induced Transparency. Physics Today. July 1997. 36-42.
  • K.J. Boller, A. Imamgolu, and S.E. Harris. Observation of Electromagnetically Induced Transparency. PRL. 66(20): 2593-2596,1991.
  • S.E. Harris, J.E. Field, and A. Kasapi. Dispersive Properties of Electromagnetically Induced Transparency. PRA. 46(1): r29-r32, 1992.
  • J.R. Kuklinski, U. Gaubatz, F.T. Hioe, and K. Bergmann. Adiabatic Population Transfer in a Three-Level System Driven by Delayed Laser Pulses. PRA. 40(11): 6741-6744, 1989.
  • S.E. Harris, J.E. Field, and A. Imamoglu. Nonlinear Optical Processes using Electromagnetically Induced Transparency. PRL. 64(10): 1107-1110, 1990.
  • L.V. Hau, S.E. Harris, Z. Dutton, and C.H. Behroozi. Light Speed Reduction to 17 Meters per Second in an Ultracold Atomic Gas. Nature. 397, 594-598, 1999.
  • M. Kash et al. Ultraslow Group Velocity and Enhanced Optical Effects in a Coherently Driven Hot Atomic Gas. PRL. 82(26):5229-5232, 1999.
  • D. Budker, D.F. Kimball, S.M. Rochester, and V.V. Yashchuk. Nonlinear Magneto-optics and Reduced Group Velocity of Light in Atomic Vapor with Slow Ground State Relaxatoin. PRL. 83(9):1767-1770, 1999.
  • A.V. Turukhin et al. Observation of Ultraslow and Stored Light Pulses in a Solid. PRL. 88(2):23602, 2002.