Gain-assisted superluminal light propagation

  title={Gain-assisted superluminal light propagation},
  author={L. J. Wang and Alex Kuzmich and Arthur Dogariu},
Einstein's theory of special relativity and the principle of causality imply that the speed of any moving object cannot exceed that of light in a vacuum (c). Nevertheless, there exist various proposals for observing faster-than- c propagation of light pulses, using anomalous dispersion near an absorption line, nonlinear and linear gain lines, or tunnelling barriers. However, in all previous experimental demonstrations, the light pulses experienced either very large absorption or severe… 
Transparent anomalous dispersion and superluminal light-pulse propagation at a negative group velocity
Anomalous dispersion cannot occur in a transparent passive medium where electromagnetic radiation is being absorbed at all frequencies, as pointed out by Landau and Lifshitz. Here we show, both
Signal velocity and quantum fluctuation in superluminal light pulse propagation
Pulse propagation with a superluminal group velocity is a rather counterintuitive phenomenon that at first might appear to violate the special theory of relativity’s pillar statement that no signal
On the apparent superluminality of evanescent waves.
This paper shows that the observations of superluminal and non-causal propagation of evanescent pulses under the conditions of frustrated internal reflection are only apparent, and that they can be simply explained employing an explicitly (sub)luminals causal theory.
Superluminal nonlinear anti-echos
We investigate the possibility of a superluminal photon anti-echo in a degenerate four-wave mixing configuration when two pulses vvith different carrier frequencies collide in a nonlinear sample. An
Superluminal Light Pulse Propagation at a Negative Group Velocity
Anomalous dispersion cannot occur in a transparent, passive medium where electromagnetic radiation is being absorbed at all frequencies, as pointed out by Landau and Lifshitz. Here we show, using
Absorption-free superluminal light propagation in a Landau-quantized graphene
In recent years, control of group velocity of light has attracted enormous interest. One of the main challenges is to realize an absorption-free fast or slow light propagation. Here, we study
Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system
The propagation of a probe laser field in a cavity optomechanical system with a Bose-Einstein condensate is studied. The transmission properties of the system are investigated and it is shown that
Recovering the propagation delay of an optical pulse.
It is shown that a laser pulse propagating in an atomic vapor, quasi resonant with an inverted transition and in conditions of anomalous dispersion, moves faster if it is previously retarded in a cell containing the same medium with no population inversion.
Superluminal reflection and transmission of light pulses via resonant four-wave mixing in cesium vapor.
It is found that the simultaneous superluminal light reflection and transmission can be reached when the power of the backward field becomes closer or equal to the forward power, in this case the periodical absorption modulation for photonic structure is established in atoms.
Phase-controlled transparent superluminal light propagation in a Doppler-broadened four-level N-type system
The propagation of a weak probe field in a four-level N-type quantum system in the presence of spontaneously generated coherence (SGC) is theoretically investigated. The optical properties of the


Light speed reduction to 17 metres per second in an ultracold atomic gas
Techniques that use quantum interference effects are being actively investigated to manipulate the optical properties of quantum systems. One such example is electromagnetically induced transparency,
Optical pulse propagation at negative group velocities due to a nearby gain line.
  • Bolda, Garrison, Chiao
  • Physics
    Physical review. A, Atomic, molecular, and optical physics
  • 1994
It is shown that a classical Gaussian pulse with such a carrier frequency will propagate at the negative group velocity for many atomic plasma wavelengths, before dispersion deforms the pulse shape.
Superluminous laser pulse in an active medium.
A stationary solitary solution in the accelerated frame is obtained from the model equations and simulations thereof for the laser, plasma and atoms.
The dynamics of resonant light propagation in rubidium vapor in a cell with antirelaxation wall coating are investigated. We change the polarization of the input light and measure the time dependence
Propagation of light pulses in a laser amplifier
The problem of a light pulse propagating in a nonlinear laser medium is investigated. The electromagnetic field is treated classically and the active medium consists of thermally moving atoms which
Superluminal (but causal) propagation of wave packets in transparent media with inverted atomic populations.
  • Chiao
  • Physics
    Physical review. A, Atomic, molecular, and optical physics
  • 1993
The propagation of limited-bandwidth signals, such as Gaussian wave packets, tuned to a transparent spectral region far below the resonance of an inverted two-level atomic medium, can be
We report the observation of small group velocities of order 90 m/s and large group delays of greater than 0.26 ms, in an optically dense hot rubidium gas ( $\ensuremath{\approx}360\mathrm{K}$).
Measurement of the single-photon tunneling time.
Using a two-photon interferometer, the time delay for a photon to tunnel across a barrier consisting of a 1.1-μm-thick 1D photonic band-gap material is measured, consistent with the group delay («phase time»), but not with the semiclassical time.
Linear Pulse Propagation in an Absorbing Medium
The pulse velocity in the linear regime in samples of GaP: N with a laser tuned to the bound $A$-exciton line is measured with use of a picosecond time-of-flight technique. The pulse is seen to
Two theorems for the group velocity in dispersive media.
  • Bolda, Chiao, Garrison
  • Mathematics
    Physical review. A, Atomic, molecular, and optical physics
  • 1993
Two theorems on the group velocity are presented, one of which is more widely applicable to propagation in waveguides or through multilayer dielectrics, and the other to dispersion in a medium with two resonance lines, where the group speed is abnormal within the absorption line and outside the gain line.