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arXiv:2512.13518

Multi-Photon Lasing Phenomena in Quantum Dot-Cavity QED

Lavakumar Addepalli

quant-phcond-mat.mes-hallSubmitted Dec 15, 2025• Announced Dec 16, 2025• 0 citations
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Abstract

Multi-photon lasing has been realized in systems with strong nonlinear interactions between emitters and cavity modes, where single-photon processes are suppressed. Coherence between the internal states of a quantum emitter, or among multiple emitters, plays a key role. Such continuous nonclassical sources of light can find applications in quantum computation, quantum sensing, quantum metrology, and quantum communication. This thesis explores the multi-photon lasing phenomena in various quantum dot-photonic crystal cavity quantum electrodynamic (QED) setups. Exciton-phonon interactions are inevitable in such systems and are incorporated using the polaron-transformed master equation. The Born-Markov approximation is employed to obtain the reduced density matrix rate equation. Using quantum laser theory, we derived the Scully-Lamb laser rate equations and evaluated the single- and multi-photon excess emission rates defined as the difference between emission and absorption rates into the cavity mode without mean-field approximations. We investigated cooperative two-photon lasing, correlated emission lasing, hyperradiant lasing, non-degenerate two-mode two-photon lasing, and continuous variable entanglement in open quantum systems with single or multiple semiconductor quantum dots (two-level, three-level, and four-level) driven coherently/incoherently and coupled to single/ bimodal cavities.

Comments
Thesis submitted to the Indian Institute of Technology Mandi

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Multi-photon lasing has been realized in systems with strong nonlinear interactions between emitters and cavity modes, where single-photon processes are suppressed. Coherence between the internal states of a quantum emitter, or among multiple emitters, plays a key role. Such continuous nonclassical sources of light can find applications in quantum computation, quantum sensing, quantum metrology, and quantum communication.
This thesis explores the multi-photon lasing phenomena in various quantum dot-photonic crystal cavity quantum electrodynamic (QED) setups. Exciton-phonon interactions are inevitable in such systems and are incorporated using the polaron-transformed master equation. The Born-Markov approximation is employed to obtain the reduced density matrix rate equation. Using quantum laser theory, we derived the Scully-Lamb laser rate equations and evaluated the single- and multi-photon excess emission rates defined as the difference between emission and absorption rates into the cavity mode without mean-field approximations. We investigated cooperative two-photon lasing, correlated emission lasing, hyperradiant lasing, non-degenerate two-mode two-photon lasing, and continuous variable entanglement in open quantum systems with single or multiple semiconductor quantum dots (two-level, three-level, and four-level) driven coherently/incoherently and coupled to single/ bimodal cavities.
We propose cooperative two-photon lasing in two quantum dots coupled to a single-mode photonic crystal cavity. We consider both quantum dots are driven either incoherently or coherently using an external pump. We incorporate exciton-phonon coupling using polaron transformed master equation. Using quantum laser theory, single- and multiphoton excess emission rates (difference between emission and absorption) into cavity mode are investigated. The single- and two-photon excess emission rates contribute to cavity photons, predominantly. Varying the pump strength can lead to single-photon excess emission rate change from negative to positive, and thus, by appropriately selecting pump strength, single-photon excess emission rate can be made negligible.
We investigate the phenomenon of correlated emission lasing in a coherently driven single quantum dot coupled to a bimodal photonic crystal cavity, utilizing a master equation to describe the system dynamics. To account for exciton-phonon interactions, we incorporate a nonperturbative approach through a polaron transformed master equation. By analyzing fluctuations in the Hermitian operators associated with relative and average phase, we derive a Fokker-Planck equation to assess phase drift and diffusion coefficients, demonstrating that correlated emission suppresses quantum noise in the presence of exciton-phonon interaction at low temperature. Additionally, we calculate the single- and two-photon excess emission rates (difference between emission and absorption rates) into the cavity modes and explore the generation of continuous-variable entanglement between these modes.
Abstract We propose methods for the realization of a continuous two-photon source using a coherently driven quantum dot embedded inside a photonic crystal cavity. We analyze the steady state population in quantum dot energy levels and field inside the cavity mode. We find conditions for population inversion in coherently driven and incoherently driven quantum dots. We discuss the effect of phonon coupling using the recently developed polaron transformed master equation at low temperatures. We show that on increasing temperature, two-photon gain decreases and single photon gain increases, due to phonon-assisted cavity mode feeding. We also propose a scheme for generating a squeezed state of field using four wave mixing.
Collective spontaneous emission occurs when multiple quantum emitters decay into common radiation modes, resulting in enhanced or suppressed emission. Here, we find the quantum state of light collectively emitted from emitters exhibiting quantum correlations. We unveil under what conditions the quantum correlations are not lost during the emission but are instead transferred to the output light. Under these conditions, the inherent nonlinearity of the emitters can be tailored to create desired photonic states in the form of traveling single-mode pulses, such as Gottesman-Kitaev-Preskill and Schrödinger-cat states, that are useful for error correction in quantum computation. To facilitate such predictions, our work reveals the multimode nature of collective spontaneous emission, capturing the role of the emitters' positions, losses, interactions, and beyond-Markov dynamics on the emitted quantum state of light. We present manifestations of these effects in different physical systems, with examples of cavity QED, waveguide QED, and atomic arrays with up to a few dozen emitters. Our findings suggest paths for creating and manipulating multiphoton quantum light for bosonic codes in continuous-variable-based quantum computation, communications, and sensing.
Abstract Spontaneous two-photon emission is a process in which the transition between two quantum states happens via simultaneous emissions of two identical photons. Such second-order quantum radiation is of paramount importance in astrophysics, atomic physics, and quantum technology. In particular, on-demand spontaneous two-photon emission from single quantum emitters has long been envisioned to revolutionize photonic quantum science and technology. To date, experimental realizations of two-photon emission at the single quanta level are still highly challenging yet elusive due to their low probabilities. In this work, we explore spontaneous two-photon emission from a single semiconductor quantum dot deterministically coupled to a high-quality microcavity in which the cavity resonances greatly enhance both excitation and emission processes. When the cavity is resonant to the half energy of the biexciton, the strong vacuum field in the cavity mode drives the biexciton to the ground state and simultaneously emits two photons into the cavity mode, resulting in two-photon emissions with a record brightness comparable to the competing single-photon process and sub-nanowatt power consumption. For the first time, the quantum nature associated with spontaneous two-photon emissions in the cavity quantum electrodynamics regime has been investigated via photon statistics measurements. Furthermore, spontaneous two-photon emission is exploited to build unconventional entangled quantum light sources with the unique advantage of combining the best of two worlds: near-unity entanglement fidelity for spontaneous parametric down-conversion source and on-demand photon emissions for atomic quantum emitters. Our work provides unprecedented insights into the two-photon process in the quantum regime and opens an unexplored avenue for pursuing optically reconfigurable quantum light sources with nonlinear quantum radiations.