Stimulated Raman transitions are often used in an atom interferometer (AI) for wave packet manipulation. Normally, two lasers with different frequencies contained in a Raman beam are combined first and then amplified by a single tapered amplifier (TA). This configuration can simplify the laser system of the AI, however, additional sidebands will be generated by the TA because of the nonlinear effect in the TA. In this work, the impact of additional sidebands generated with a single TA on the AI is studied. We first observe the additional sidebands in a Raman laser by a Fabry-Pérot interferometer (FPI), and the additional sidebands will be greatly suppressed by reducing the injection laser power of the TA. This is also confirmed by observing the position-dependent Raman transitions induced by additional sidebands at different injection power in an AI. However, the phase shifts induced by additional sidebands are not reduced obviously when the injection power of the TA is reduced. Therefore, it is necessary to separately amplify two lasers contained in the Raman laser by two TAs for a high precision AI. The spectroscopy of Raman laser generated by two TAs is also measured by the FPI, and the impact of additional sidebands on the AI is eliminated. This work has guiding significance for the design of the laser system in a high-precision AI.Stimulated Raman transitions are often used in an atom interferometer (AI) for wave packet manipulation. Normally, two lasers with different frequencies contained in a Raman beam are combined first and then amplified by a single tapered amplifier (TA). This configuration can simplify the laser system of the AI, however, additional sidebands will be generated by the TA because of the nonlinear effect in the TA. In this work, the impact of additional sidebands generated with a single TA on the AI is studied. We first observe the additional sidebands in a Raman laser by a Fabry-Pérot interferometer (FPI), and the additional sidebands will be greatly suppressed by reducing the injection laser power of the TA. This is also confirmed by observing the position-dependent Raman transitions induced by additional sidebands at different injection power in an AI. However, the phase shifts induced by additional sidebands are not reduced obviously when the injection power of the TA is reduced. Therefore, it is necessary to separately amplify two lasers contained in the Raman laser by two TAs for a high precision AI. The spectroscopy of Raman laser generated by two TAs is also measured by the FPI, and the impact of additional sidebands on the AI is eliminated. This work has guiding significance for the design of the laser system in a high-precision AI.

Optics LettersAug 29, 20221 citation

Cascading amplifiers can create exponentially large coherence

Lucas A. Ostrowski, Giacomo Pantaleoni, Howard M. Wiseman +1 more

A standard laser beam has photon degeneracy, or coherence, $\mathfrak{C}$ , of at most $8μ^2$ , where $μ$ is the number of photons in the laser itself. Even quantum-engineered lasers, if required to produce a beam with the standard statistical properties, have limited coherence, scaling as $μ^4$ . Moreover, such lasers (still unrealised) require very unconventional gain and output-coupling mechanisms. Here, we propose a different path to increasing $\mathfrak{C}$ : cascaded linear amplifiers, with conventional couplings. By dropping the requirement on the beam's properties, this approach can, in theory, achieve $\mathfrak{C}$ scaling exponentially in $μ$ . Here $μ$ is the total source excitation number, across all the amplifiers. Two amplifiers suffice to surpass the standard $μ^2$ scaling.A standard laser beam has photon degeneracy, or coherence, $\mathfrak{C}$, of at most $8μ^2$, where $μ$ is the number of photons in the laser itself. Even quantum-engineered lasers, if required to produce a beam with the standard statistical properties, have limited coherence, scaling as $μ^4$. Moreover, such lasers (still unrealised) require very unconventional gain and output-coupling mechanisms. Here, we propose a different path to increasing $\mathfrak{C}$: cascaded linear amplifiers, with conventional couplings. By dropping the requirement on the beam's properties, this approach can, in theory, achieve $\mathfrak{C}$ scaling exponentially in $μ$. Here $μ$ is the total source excitation number, across all the amplifiers. Two amplifiers suffice to surpass the standard $μ^2$ scaling.

quant-pharXiv:2607.28716Aug 3, 20260 citations

Quantum Theory of Laser Amplifiers.

G. L. Mander

Jan 1, 19910 citations

Amplifying Two-Mode Squeezing in Nanomechanical Resonators

Muhdin Abdo Wodedo, Tesfay Gebremariam Tesfahannes, Tewodros Yirgashewa Darge +2 more

Quantum squeezing plays a crucial role in enhancing the precision of quantum metrology and improving the efficiency of quantum information processing protocols. We thus propose a scheme to amplify two-mode squeezing in nanomechanical resonators, harnessing parametric amplification and two-tone laser controls. The red-detuned laser drives facilitate the cooling of the nanomechanical resonators down to their ground state and allow optimal quantum state transfer in the weak-coupling, resolved sideband regime. In particular, the competing blue-detuned lasers in the driving pairs induce displacement squeezing in mechanical resonators. Thus, the quantum state transfer of the squeezing in nanomechanical resonators and the intracavity correlated photons of the parametric amplifier significantly enhance the two-mode mechanical squeezing. Notably, increasing the coupling strength of the red detuned laser and the ratio of blue-to-red detuned laser dramatically amplifies the two-mode mechanical squeezing under realistic experiment parameters of a typical optomechanical system. Our findings reveal that the proposed cooperative mechanism effectively enhances the level of two-mode mechanical squeezing with a considerable improvement and demonstrates exceptional resilience to thermal noise.Quantum squeezing plays a crucial role in enhancing the precision of quantum metrology and improving the efficiency of quantum information processing protocols. We thus propose a scheme to amplify two-mode squeezing in nanomechanical resonators, harnessing parametric amplification and two-tone laser controls. The red-detuned laser drives facilitate the cooling of the nanomechanical resonators down to their ground state and allow optimal quantum state transfer in the weak-coupling, resolved sideband regime. In particular, the competing blue-detuned lasers in the driving pairs induce displacement squeezing in mechanical resonators. Thus, the quantum state transfer of the squeezing in nanomechanical resonators and the intracavity correlated photons of the parametric amplifier significantly enhance the two-mode mechanical squeezing. Notably, increasing the coupling strength of the red detuned laser and the ratio of blue-to-red detuned laser dramatically amplifies the two-mode mechanical squeezing under realistic experiment parameters of a typical optomechanical system. Our findings reveal that the proposed cooperative mechanism effectively enhances the level of two-mode mechanical squeezing with a considerable improvement and demonstrates exceptional resilience to thermal noise.

arXiv:2508.18972IEEE Transactions on Quantum EngineeringJan 1, 202513 citations

Quantum Control of Intensity in Semiconductor Laser Amplifiers

Magnus Höijer, Anders Karlsson

Springer eBooksJan 1, 19960 citations

A standard laser beam has photon degeneracy, or coherence,

\mathfrak{C}

, of at most

8μ^2

, where

μ

is the number of photons in the laser itself. Even quantum-engineered lasers, if required to produce a beam with the standard statistical properties, have limited coherence, scaling as

μ^4

. Moreover, such lasers (still unrealised) require very unconventional gain and output-coupling mechanisms. Here, we propose a different path to increasing

\mathfrak{C}

: cascaded linear amplifiers, with conventional couplings. By dropping the requirement on the beam's properties, this approach can, in theory, achieve

\mathfrak{C}

scaling exponentially in

μ

. Here

μ

is the total source excitation number, across all the amplifiers. Two amplifiers suffice to surpass the standard

μ^2

scaling.