Squeezing Phase Diffusion

Cialdi, S.; Suerra, Edoardo; Olivares, Stefano; Capra, S.; Paris, Matteo G. A.

doi:10.1103/physrevlett.124.163601

Cited by 13 publications

(18 citation statements)

References 34 publications

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“…Another reason to consider coherent states is that quantum optical experiments are typically performed with lasers and the state of laser light can be effectively modelled as coherent. In fact, a recent experiment demonstrating phase diffusion and how it can be countered using squeezing was performed with a coherent state input [13]. Aside from these advantages of coherent states, there are also reasons for not considering other commonly used quantum-optical states: First, for phase diffusion, states with perfect angular symmetry-the vacuum, thermal, or number states-cannot be used as input models as they have a maximally diffused phase.…”

Section: Amplifier Parameter Regime and Input Signal Modelmentioning

confidence: 99%

“…The advantage of the inverse-number expansion can also be seen in the complexity of g 3 (t), where it would have been somewhat tedious to derive by solving a set of three coupled differential equations. Of course, after obtaining (25) one still has to calculate E[Φ 2 (t)] according to (15), and then the variance defined by (13). The expression for E[Φ 2 (t)] thus entails an integral of g n (t).…”

Section: Inverse-number Expansionmentioning

confidence: 99%

“…Aside from fundamental interests, phase diffusion has also been shown to be useful for quantum random number generation [9][10][11][12]. More recently it has also been used to demonstrate the applicability of phase squeezing as a means to reduce phase noise in linear amplifiers [13].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phase diffusion and the small-noise approximation in linear amplifiers: Limitations and beyond

Chia

Hajdušek

Fazio

et al. 2019

Quantum

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The phase of an optical field inside a linear amplifier is widely known to diffuse with a diffusion coefficient that is inversely proportional to the photon number. The same process occurs in lasers which limits its intrinsic linewidth and makes the phase uncertainty difficult to calculate. The most commonly used simplification is to assume a narrow photon-number distribution for the optical field (which we call the small-noise approximation). For coherent light, this condition is determined by the average photon number. The small-noise approximation relies on (i) the input to have a good signal-to-noise ratio, and (ii) that such a signal-to-noise ratio can be maintained throughout the amplification process. Here we ask: For a coherent input, how many photons must be present in the input to a quantum linear amplifier for the phase noise at the output to be amenable to a small-noise analysis? We address these questions by showing how the phase uncertainty can be obtained without recourse to the small-noise approximation. It is shown that for an ideal linear amplifier (i.e. an amplifier most favourable to the small-noise approximation), the small-noise approximation breaks down with only a few photons on average. Interestingly, when the input strength is increased to tens of photons, the small-noise approximation can be seen to perform much better and the process of phase diffusion permits a small-noise analysis. This demarcates the limit of the small-noise assumption in linear amplifiers as such an assumption is less true for a nonideal amplifier.1 The semiclassical approximation replaces the bosonic annihilation operatorâ by â + δâ and neglects (δâ) 2 and terms with higher order in δâ, where δâ is the deviation ofâ from its average value.Accepted in Quantum 2019-10-09, click title to verify. Published under CC-BY 4.0.

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Section: Amplifier Parameter Regime and Input Signal Modelmentioning

confidence: 99%

Section: Inverse-number Expansionmentioning

confidence: 99%

See 1 more Smart Citation

Phase diffusion and the small-noise approximation in linear amplifiers: Limitations and beyond

Chia

Hajdušek

Fazio

et al. 2019

Quantum

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“…In our analysis, we focus on the relevant class of Gaussian probes, namely, states that exhibit a Gaussian Wigner function [21,22]. In particular, we consider the performance of the so-called displaced coherent states, that can be easily generated and manipulated by current quantum optics technology [23]. Coherent states are usually considered to be the closest quantum states to classical ones.…”

Section: Optimal Probes For Individual Estimationmentioning

confidence: 99%

Quantum Probes for the Characterization of Nonlinear Media

Candeloro

Razavian

Piccolini

et al. 2021

Entropy

Self Cite

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Active optical media leading to interaction Hamiltonians of the form H=λ˜(a+a†)ζ represent a crucial resource for quantum optical technology. In this paper, we address the characterization of those nonlinear media using quantum probes, as opposed to semiclassical ones. In particular, we investigate how squeezed probes may improve individual and joint estimation of the nonlinear coupling λ˜ and of the nonlinearity order ζ. Upon using tools from quantum estimation, we show that: (i) the two parameters are compatible, i.e., the may be jointly estimated without additional quantum noise; (ii) the use of squeezed probes improves precision at fixed overall energy of the probe; (iii) for low energy probes, squeezed vacuum represent the most convenient choice, whereas for increasing energy an optimal squeezing fraction may be determined; (iv) using optimized quantum probes, the scaling of the corresponding precision with energy improves, both for individual and joint estimation of the two parameters, compared to semiclassical coherent probes. We conclude that quantum probes represent a resource to enhance precision in the characterization of nonlinear media, and foresee potential applications with current technology.

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“…where D(α) = e αa † −α * a is the displacement operator, |0 the vacuum state and {|n } n∈N is the Fock basis. A displaced squeezed state is defined as follows [21] |α, ξ = D(α) Ŝ(ξ)|0 (23) where Ŝ(ξ) = exp 1 2 ξ(â † ) 2 − ξ * â2 is the single-mode squeezing operator and ξ ∈ C is the complex squeezing parameter. If α = 0, we obtain the so-called squeezed vacuum state, whereas for ξ = 0 we have a coherent state.…”

Section: Optimal Probes For Individual Estimationmentioning

confidence: 99%

Quantum probes for the characterization of nonlinear media

Candeloro,

Razavian,

Piccolini

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Active optical media leading to interaction Hamiltonians of the form H = λ (a + a † ) ζ represent a crucial resource for quantum optical technology. In this paper, we address the characterization of those nonlinear media using quantum probes, as opposed to semiclassical ones. In particular, we investigate how squeezed probes may improve individual and joint estimation of the nonlinear coupling λ and of the nonlinearity order ζ. Upon using tools from quantum estimation, we show that: i) the two parameters are compatible, i.e. the may be jointly estimated without additional quantum noise; ii) the use of squeezed probes improves precision at fixed overall energy of the probe; iii) for low energy probes, squeezed vacuum represent the most convenient choice, whereas for increasing energy an optimal squeezing fraction may be determined; iv) using optimized quantum probes, the scaling of the corresponding precision with energy improves, both for individual and joint estimation of the two parameters, compared to semiclassical coherent probes. We conclude that quantum probes represent a resource to enhance precision in the characterization of nonlinear media, and foresee potential applications with current technology.

show abstract

Squeezing Phase Diffusion

Cited by 13 publications

References 34 publications

Phase diffusion and the small-noise approximation in linear amplifiers: Limitations and beyond

Phase diffusion and the small-noise approximation in linear amplifiers: Limitations and beyond

Quantum Probes for the Characterization of Nonlinear Media

Quantum probes for the characterization of nonlinear media

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