Limitations on the quantum non-Gaussian characteristic of Schrödinger kitten state generation

Abstract

A quantitative analysis is conducted on the impacts of experimental imperfections in the input state, the detector properties, and their interactions on photon-subtracted squeezed vacuum states in terms of a quantum non-Gaussian character witness and Wigner function. Limitations of the nonclassicality and quantum non-Gaussian characteristic of Schrödinger kitten states are identified and addressed. The detrimental effects of a photon-number detector on the generation of odd Schrödinger kitten states at near-infrared wavelengths (∼860 nm) and telecommunication wavelengths (∼1550 nm) are presented and analysed. This analysis demonstrates that the high dark count probability of telecommunication-wavelength photon-number detectors significantly undermines the negativity of the Wigner function in Schrödinger kitten state generation experiments. For a one-photon-subtracted squeezed vacuum state at ∼1550 nm, an avalanche photodiode-based photon-numberresolving detector provides no significant advantage over a non-photon-numberresolving detector when imperfections, such as dark count probability and inefficiency, are taken into account.

Control engineering of continuous-mode single-photon states: a review

“…After interaction, output field, represented by its integrated annihilation operator B out and creation operator B * out , is also in a single-photon state with pules shape . Due to measurement imperfection (measurement inefficiency), the output field �1 ⟩ may be contaminated [12,66]. This is usually mathematically modeled mixing �1 ⟩ with an additional quantum vacuum through a beam splitter, as shown in Fig.…”

“…The output single-photon state is denoted by �1 ⟩ . To account for the imperfectness of experiment [66], a beamsplitter is added which mixes �1 ⟩ with a vacuum noise. Both of the signals in the output ports of the beamsplitter are measured to improving the filtering effect commutative von Neumann algebra Y t is generated by the past measurement observations {Y 1 (s), Y 2 (s) ∶ t 0 ⩽ s ⩽ t} .…”

“…Applications of Schrödinger cat states in quantum teleportation, quantum computation, and quantum metrology can be found in, e.g., [80][81][82]. A scheme for generating Schrödinger cat states is proposed in [66]. In what follows, we use the linear systems…”

Single‐photon quantum filtering with multiple measurements

“…In quantum optics experiments, there may exist some limitations due to the impure input state and the imperfect measurements. A set of experimental imperfections in the input, the photon subtraction, and the detector were taken into account in the work of Song et al The effects of various experimental parameters on the Schrödinger kitten state generation have been discussed in terms of non‐Gaussian property witness and the origin of the Wigner function. A finite‐dimensional Markov system with quantum nondemolition measurements was considered in the work of Amini et al Quantum filters and the robustness property for both perfect and imperfect measurements have been analyzed; the convergence of the controlled system is ensured when imperfect measurements are corrupted by random errors.…”

Quantum non-Gaussianity from a large ensemble of single photon emitters

“…It has been introduced recently a methodology of criteria of quantum non-Gaussianity that witnesses more precisely the discrete character of light. Quantum non-Gaussianity donates incompatibility of a state with any mixture of squeezed coherent states [12][13][14][15][16]. Because this feature excludes a more general set of states, it differs fundamentally from non-classicality and imposes a more appropriate condition on required quantum features.…”