arXiv subjects

Stanisław Kurzyna

Publications and source records attributed to Stanisław Kurzyna.

7 recordsLinked to original sources

arXiv2026

Multiplexed storage and interaction of Rydberg spinwaves via the gradient echo memory protocol

Collective Rydberg excitations offer strong and controllable interactions for quantum information processing, sensing, and nonlinear quantum optics, but their integration with temporally or spectrally multiplexed schemes, such as the Gradient Echo Memory (GEM) protocol, is hindered by rapid motional dephasing caused by the large spinwave wavevector. We demonstrate a new type of multi-photon addressing and interfacing scheme (with levels following the shape of the letter Ń) that allows us to generate collective Rydberg excitations with near-zero momentum transfer, extending the Rydberg spinwave lifetime almost tenfold. The scheme relies on two additional off-resonant driving fields arranged at a magic angle, forming a closed wavevector loop while remaining compatible with GEM-induced inhomogeneous broadening. This enables storage and manipulation of long-lived Rydberg spinwaves in a multimode quantum memory. Using microwave coupling between neighboring Rydberg states, we can control the attenuation between stored excitation modes by interaction-induced decay and demonstrate interaction-controlled diffraction of a retrieved optical signal. Our results reestablish compatibility between Rydberg excitations and GEM, providing a route toward multimode quantum memories with controllable long-range interactions and applications in quantum networking, sensing, and quantum information processing.

quant-ph↗

arXiv2026

Hybrid quantum memory leveraging slow-light and gradient-echo duality

We demonstrate a hybrid quantum memory that combines Gradient Echo Memory (GEM) and Electromagnetically Induced Transparency (EIT) protocols for reversible mapping between light and atomic coherence. By leveraging GEM and EIT complementarity, we realize time-to-frequency and frequency-to-time conversion mechanisms for spectro-temporal modes. This capability provides a versatile tool for quantum communication, where coherent frequency-time conversion enhances network interoperability. In addition, the protocol may enable fundamental studies of atomic coherence, including investigations of Rydberg polaritons and mapping of single Rydberg excitations and ionic impurities.

quant-ph↗

arXiv2025

Microwave-field quantum metrology with inherent robustness against detection losses enabled by Rydberg interactions

Quantum sensing and metrology present one of the most promising near-term applications in the field of quantum technologies, with quantum sensors enabling unprecedented precision in measurements of electric, magnetic or gravitational fields and displacements. Experimental loss at the detection stage remains one of the key obstacles to achieving a truly quantum advantage in many practical scenarios. Here, we combine the capabilities of Rydberg atoms to both sense external fields and be used for quantum information processing, thereby largely overcoming the issue of detection losses. While utilising the large dipole moments of Rydberg atoms in an ensemble to achieve a $\SI{39}{\nV\per\cm \hertz\tothe{-1/2}}$ sensitivity, we employ inter-atomic dipolar interactions to take advantage of an error-prevention protocol that protects information against conventional losses at the detection stage. Counterintuitively, the protocol's idea is based on introducing an additional non-linear, lossy quantum channel, which results in a 3.3-fold enhancement of Fisher information. The presented results pave the way for broader adoption of quantum-information-inspired enhancements enabled by intrinsic interactions present in a sensor system, and more broadly in practical quantum metrology and communication, without the need for a general-purpose quantum computer.

quant-ph↗

arXiv2024

Long-lived collective Rydberg excitations in atomic gas achieved via ac-Stark lattice modulation

Collective Rydberg excitations provide promising applications ranging from quantum information processing, and quantum computing to ultra-sensitive electrometry. However, their short lifetime is an immense obstacle in real-life scenarios. The state-of-the-art methods of prolonging the lifetime were mainly implemented for ground-state quantum memories and would require a redesign to effectively work on different atomic transitions. We propose a protocol for extending the Rydberg excitation lifetime, which in principle can freeze the spin-wave and completely cancel the effects of thermal dephasing. The protocol employs off-resonant ac-Stark lattice modulation of spin waves by interfering two laser beams on the atomic medium. Our implementation showed that the excitation lifetime can be extended by an order of magnitude, paving the way towards more complex protocols for collective Rydberg excitations.

quant-ph↗

arXiv2024

Variable electro-optic shearing interferometry for ultrafast single-photon-level pulse characterization

Despite the multitude of available methods, the characterisation of ultrafast pulses remains a challenging endeavour, especially at the single-photon level. We introduce a pulse characterisation scheme that maps the magnitude of its short-time Fourier transform. Contrary to many well-known solutions it does not require nonlinear effects and is therefore suitable for single-photon-level measurements. Our method is based on introducing a series of controlled time and frequency shifts, where the latter is performed via an electro-optic modulator allowing a fully-electronic experimental control. We characterized the full spectral and temporal width of a classical and single-photon-level pulse and successfully reconstructed their spectral phase and amplitude. The method can be extended by implementing a phase-sensitive measurement and is naturally well-suited to partially-incoherent light.

physics.optics↗

arXiv2024

Spectrum-to-position mapping via programmable spatial dispersion implemented in an optical quantum memory

Spectro-temporal processing is essential in reaching ultimate per-photon information capacity in optical communication and metrology. In contrast to the spatial domain, complex multimode processing in the time-frequency domain is however challenging. Here we propose a protocol for spectrum-to-position conversion using spatial spin wave modulation technique in gradient echo quantum memory. This way we link the two domains and allow the processing to be performed purely on the spatial modes using conventional optics. We present the characterization of our interface as well as the frequency estimation uncertainty discussion including the comparison with Cramér-Rao bound. The experimental results are backed up by numerical numerical simulations. The measurements were performed on a single-photon level demonstrating low added noise and proving applicability in a photon-starved regime. Our results hold prospects for ultra-precise spectroscopy and present an opportunity to enhance many protocols in quantum and classical communication, sensing, and computing.

quant-ph↗

arXiv2024

Experimental implementation of the optical fractional Fourier transform in the time-frequency domain

The fractional Fourier transform (FrFT), a fundamental operation in physics that corresponds to a rotation of phase space by any angle, is also an indispensable tool employed in digital signal processing for noise reduction. Processing of optical signals in their time-frequency degree of freedom bypasses the digitization step and presents an opportunity to enhance many protocols in quantum and classical communication, sensing and computing. In this letter, we present the experimental realization of the fractional Fourier transform in the time-frequency domain using an atomic quantum-optical memory system with processing capabilities. Our scheme performs the operation by imposing programmable interleaved spectral and temporal phases. We have verified the FrFT by analyses of chroncyclic Wigner functions measured via a shot-noise limited homodyne detector. Our results hold prospects for achieving temporal-mode sorting, processing and super-resolved parameter estimation.

quant-ph↗