Title: Photon Switching by
1Photon Switching by Quantum Interference
??? ???????
2Transition Diagram
3The Three-Fold Entangled State
where 1 or 0 in the  ?s,  ?p, and  ?f denotes
presence or absence of the switching, probe, and
fluorescence photons measured by the detectors.
Requirements OD ? 10 and ? ? 10-3?.
4Frequency Spectrum
Wc 1.5 G Ws 1.5 G
Thin and thick lines are the spectra of probe
absorption without and with the switching field,
respectively.
5Steady-State Properties at the Resonance
where OD is the optical density defined by Iout
Iin e-OD and TD is the propagation delay time.
For ?s ? ?p, large OD(0,0) and negligible ? are
the requirements to satisfy both EIT and PS
conditions.
6Perturbation Method
7One Photon per ?2 Switches the Medium from
Transparency to Opacity
8Rise Time of the Probe Absorption
9Transient Behaviors of the Probe Absorption
10Defects in the Current Calculation
?in(t)
?(t)
?out(t)
11The More Precise Calculation
Probe propagation
Switching propagation
Atomic coherence
?
12Pulse Propagation in the EIT Medium
For N 0,
In general, solve the following equations
numerically.
13Slice Sample and Neglect Propagation Delay
However, Im?31/? can diverge.
14Treat ??/?t Term as Perturbation
. . . . . .
Find the analytical solution of ?31(?p(x,t)) and
numerically solve the equation of probe
propagation.
Wc 0.1 and Wp,max 0.052.