Light : its generation and modification

Rohit Mukherjee, Rohit Hazra, Nitu Borgohain

This article presents a coherent phenomenon called spontaneously generated coherence (SGC) under the regime of electromagnetically induced transparency (EIT) in a three-coupled multiple quantum wells. We demonstrate that the presence of SGC in these quantum wells lead to intriguing modifications in the transparency window within the absorption spectrum. At the same time, modification of the dispersive nature is also demonstrated which enables the feasibility of the system in diverse applications based on light propagation. The absorption and dispersion responses are found to be varied by the individual strength of the first and second control fields in presence as well as in absence of SGC in the EIT regime. The positional shifting of the transparency window and simultaneous modifications in the dispersive profiles by tuning the control field detunings of both the first and second control fields are also revealed. Some absorption and dispersion contours are illustrated for getting better insights into the modifications of the optical responses via SGC. Finally, by manipulating the strength of the SGC parameter, we observe the changes in the respective position of the transparency window and dispersion curve. It is expected that the current investigations will pave novel ways for innovative applications in quantum communications, and fabrication of advanced photonic devices.

Juhyung Seo, Seungme Kang, Chaehyun Kim +7 more

ABSTRACT We present a photospike‐based true random number generator (PS‐TRNG) that exploits the intrinsic randomness from light–matter interaction and stochastic charge trapping. By integrating copper vanadate (CuV 2 O 6 ) nanostructures with a tin dioxide quantum dot (SnO 2 QD) layer, the device induces probabilistic trapping–de‐trapping dynamics, producing random photospike currents under optical pulse trains. The spike currents show high entropy and enable multi‐level random number generation beyond binary, providing ternary outputs with near‐ideal statistics (33.30% uniformity, 33.28% inter‐Hamming distance) and full success in all 15 NIST tests. We further develop an image authenticity verification system by integrating the PS‐TRNG with a mobile platform and custom‐designed circuit board, enabling hardware‐based detection of unauthorized image modifications. The random numbers are embedded as a hidden layer within the image data without degrading visual quality, enabling detection of unauthorized modifications. The system can successfully identify image modifications, even those involving highly sophisticated manipulations generated by artificial intelligence (AI)‐based image editing tools. The device maintains stable operation over 2 million cycles and remains reliable even after more than 460 days, demonstrating its long‐term stability.

Steven S. Andrews

P. S. Ramanujam, Niels Grønbech‐Jensen

We describe a modification of a nonlinear Mach-Zehnder interferorneter to produce a sub-Poissonian photon distribution and an experimental set-up to realize it. It is shown that it is possible to achieve a substantial reduction in the photon number uncertainty with a high power efficiency.