Observation of superluminal and negative group velocities in a Mach–Zehnder interferometer

Sánchez-López, Marı́a del Mar; Sánchez-Meroño, A.; Arias,; Davis, Jeffrey A.; Moreno, Ignacio

doi:10.1063/1.2969407

Cited by 24 publications

(27 citation statements)

References 15 publications

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“…The superluminal motion does not contradict causality and no information can be transmitted with velocity larger than the velocity of light. Indeed, the effect has been observed in several experiments (see e.g., [8][9][10][11]).…”

Section: Introductionmentioning

confidence: 89%

Neutrino velocity and neutrino oscillations

Minakata

Smirnov

2012

Phys. Rev. D

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We study distances of propagation and the group velocities of the muon neutrinos in the presence of mixing and oscillations assuming that Lorentz invariance holds. Oscillations lead to distortion of the ν µ wave packet which, in turn, changes the group velocity and the distance ν µ travels. We find that the change of the distance, d osc , is proportional to the length of the wave packet, σ x , and the oscillation phase, φ p , acquired by neutrinos in the π− and K− meson decay tunnel where neutrino wave packet is formed: d osc ∝ σφ p . Although the distance d osc may effectively correspond to the superluminal motion, the effect is too tiny (∼ 10 −5 cm ) to be reconciled with the OPERA result. We analyze various possibilities to increase d osc and discuss experimental setups in which d osc (corresponding to the superluminal motion) can reach an observable value ∼ 1 m.

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Section: Introductionmentioning

confidence: 89%

Neutrino velocity and neutrino oscillations

Minakata

Smirnov

2012

Phys. Rev. D

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“…This led the authors to point out this structure as a good candidate for obtaining negative group velocity. Time domain experiments performed with Gaussian acoustic pulses [32] and sinusoidally modulated RF wave packets [33] corroborated these findings. By tuning the pulse carrier frequency slightly off the transmission minima, superluminal propagation was also detected [33].…”

Section: Introductionmentioning

confidence: 58%

“…This two-path interferometer has been shown to sustain fast-light propagation for frequencies close to the transmission minima [31][32][33]. In [31], frequency-domain characterization of an asymmetric loop structure (asymmetric MZI) built with coaxial cables showed negative phase jumps around the transmission minima.…”

Section: Introductionmentioning

confidence: 96%

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Fast light in unbalanced low-loss Mach-Zehnder interferometers

2014

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An analytical approach is reported that describes previously observed fast-light regimes in linear and passive Mach-Zehnder interferometers (MZI) where the optical path difference is due to a different length of the branches. Approximate expressions are developed for the transmission coefficient and group delay spectral functions valid for frequencies close to the transmission minima ω min , where these regimes occur. It is found that the group delay at ω min verifies a simple scaling law. We demonstrate that slow light cannot arise in this system, and that tunneling and superluminal regimes appear only for low-loss devices, where the attenuation drives the change in the propagation regimes. The propagation of a sinusoidally modulated pulse train through the MZI is described, and relevant figures of merit, which are intrinsic to the system and universal for any operative spectral range, are determined. The theoretical approach is illustrated by simulations of a silicon-based interferometer designed for advancing pulses at 1.55 μm. Also, previously reported experimental results in the radiofrequency range are interpreted in the framework of the model.

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“…Unlike these systems, we recently demonstrated superluminal and negative group velocity regimes in a linear and passive Mach-Zehnder interferometer 13 (MZI). We showed that anomalous dispersion in a narrow frequency region around the interferometer's transmission minima is strong enough to hold these propagation regimes without the need of periodically microstructuring, doping, or using non-linear media in the interferometer's arms.…”

Section: Introductionmentioning

confidence: 98%

Group velocity control in multiple-beam and Mach-Zehnder interferometers

et al. 2010

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In this work, we demonstrate the existence of abnormal pulse propagation regimes in linear and passive multiple-beam interferometers, where the group velocity can be tuned from subluminal to superluminal values by simply changing the length of one of the interferometer's arms. Experiments are performed in the radiofrequency range by using coaxial transmission lines. The interferometers group delay is characterized both in the frequency and in the time domain. Group velocities of 2c and tunnelling with negative group velocity of -0.11c were measured for electromagnetic wave packets of 2 µs width travelling through a Mach-Zehnder interferometer. In a 4-beam interferometer, the group velocity of a 5 µs wide pulse was reduced to only 0.3c (compared to the usual value of 0.67c). The system is scalable to other frequency ranges and its implementation for narrowband optical pulses could be feasible by means of micromachining technologies. A scaling approach for advancing/delaying optical pulses at 1.55 µm is discussed. These systems are proposed as an alternative for controlling the group velocity without the need of using photonic crystals or periodically microstructuring, doping or using non-linear media.

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Observation of superluminal and negative group velocities in a Mach–Zehnder interferometer

Cited by 24 publications

References 15 publications

Neutrino velocity and neutrino oscillations

Neutrino velocity and neutrino oscillations

Fast light in unbalanced low-loss Mach-Zehnder interferometers

Group velocity control in multiple-beam and Mach-Zehnder interferometers

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