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arXiv:2610.36233

Generation of quantum light with tunable Wigner negativity with a semiconductor quantum dot

Hubert Lam, Petr Steindl, Yann Portella, Kiarn T. Laverick, Kian Hwee Lim, Juan R. Alvarez, Aristide Lemaitre, Maria Maffei, Alexia Auffeves, Dario A. Fioretto, Pascale Senellart

quant-phcond-mat.mes-hallphysics.opticsSubmitted Oct 26, 2026• Announced Oct 28, 2026• 0 citations
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Abstract

Wigner-negative states of light are key resources for quantum advantage in continuous-variable optical quantum computing. They can be produced probabilistically via frequency conversion and photon detection, or deterministically by exploiting the single-photon nonlinearity of a quantum emitter. Here, we generate such Wigner-negative states of light with a tunable negativity using a single semiconductor quantum dot in a cavity. Optical coherent control of the quantum-dot transition allows to generate a quantum superposition of zero and one photon. The generated quantum states are characterized point-by-point in the phase space through homodyne measurement. The emergence of Wigner-function negativity is observed as the excitation power is increased. After correcting for collection and propagation losses, we obtain fidelities to the ideal state and quantum purities above 95%, together with near-optimal quadrature squeezing. The ability to generate a wide variety of Wigner-negative states with mature semiconductor technology opens promising opportunities for continuous-variable optical quantum technologies.

Comments
7 pages, 4 figures

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Quantum states of light having a Wigner function with negative values represent a key resource in quantum communication and quantum information processing. Here we present the generation of such a state at the telecommunication wavelength of 1550 nm. The state is generated by means of photon subtraction from a weakly squeezed vacuum state and is heralded by the ``click'' of a single photon counter. Balanced homodyne detection is applied to reconstruct the Wigner function, also yielding the state's photon-number distribution. The heralding photons are frequency up-converted to 532 nm to allow for the use of a room-temperature (silicon) avalanche photodiode. The Wigner function reads $W(0,0)=\ensuremath{-}0.063\ifmmode\pm\else\textpm\fi{}0.004$ at the origin of phase space, which certifies negativity with more than 15 standard deviations.
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Pulsed coherent and squeezed driving of a spin-SSS emitter as a deterministic source of Wigner-negative light
Generating propagating Wigner-negative states of light is an important and difficult task for many quantum technologies. Historically, the proposed methods of creating such states have been intrinsically probabilistic, relying on conditional measurements or photon heralding. More recently, methods have been proposed involving the steady-state driving of two-level emitters, where Wigner-negative temporal modes are present in the outgoing field. We theoretically demonstrate through the simulation of a cascaded-systems model that this approach can be improved significantly with pulsed coherent or squeezed driving of a spin-1/2 emitter. This enables the deterministic generation of strongly Wigner-negative states, using only driving-source states with positive Gaussian Wigner distributions. This method is extended to the driving of a spin-SSS emitter with S≥1S\geq 1S≥1 to generate still more exotic, highly non-classical states. The array of states demonstrated in this work includes close approximations to displaced N-photon states, squeezed Schrödinger cat states, and finite-energy Gottesman-Kitaev-Preskill (GKP) states.