arXiv subjects

Sukhjit P. Singh

Publications and source records attributed to Sukhjit P. Singh.

4 recordsLinked to original sources

arXiv2026

Heralded generation of a three-mode NOON state

Entangled states of photons form the foundation of quantum communication, computation, and metrology. Yet their generation remains fundamentally constrained: in the absence of intrinsic photon-photon interactions, the generation of such states is inherently probabilistic rather than deterministic. The prevalent technique of post-selection verifies the creation of an entangled state by detecting and thus destroying it. Heralding offers a solution in which measuring ancillary photons in auxiliary modes signals the state generation without the need to measure it. Here, we introduce and experimentally demonstrate a scheme to generate a three-mode two-photon NOON state, where the detection of a single photon in one heralding mode signifies the presence of the state in three target modes. We validate the generated state by estimating a fidelity of 0.823 +/- 0.018 with respect to an ideal three-mode NOON state and certifying genuine multipartite entanglement. By virtue of the high success probability and small resource overhead of our scheme, our work provides a theoretical and experimental stepping stone for entangled multi-mode state generation, which is realizable with current technology. These multi-mode entangled states represent a key direction for linear optical quantum information that is complementary to multi-qubit state encoding.

quant-ph↗

arXiv2026

Observation of intrastate and interstate facilitation between Rydberg S, P and D levels

We report experimental results on Rydberg facilitation, whereby Rydberg levels can be excited off-resonantly in the presence of a nearby Rydberg atom because of Rydberg-Rydberg interactions, for high-lying $S$, $P$ and $D$ levels in rubidium. Facilitation is detected both through an enhancement of the number of excited atoms for off-resonant excitation (either blue or red detuning) and a positive Mandel $Q$ parameter indicating correlated excitation events (super-Poissonian counting statistics). We also calculate the pair-state potentials for the Rydberg states involved and find that our experimental results agree with the expected facilitation conditions for repulsive potentials (blue detuning) and attractive potentials (red detuning), with $P$ and $D$ states exhibiting facilitation on both sides of the resonance. Finally, we investigate inter-state facilitation between two different Rydberg levels (70 $S$ and 70 $P$).

physics.atom-ph↗

arXiv2025

Heralded generation of entanglement with photons

Entangled states of photons form the backbone of many quantum technologies. Due to the lack of effective photon-photon interactions, the generation of these states is typically probabilistic. In the prevailing but fundamentally limited generation technique, known as postselection, the target photons are measured destructively in the generation process. By contrast, in the alternative approach -- heralded state generation -- the successful creation of a desired state is verified by the detection of ancillary photons. Heralded state generation is superior to postselection in several critical ways: It enables free usage of the prepared states, allows for the success probability to be arbitrarily increased via multiplexing, and provides a scalable route to quantum information processing using photons. Here, we review theoretical proposals and experimental realizations of heralded entangled photonic state generation, as well as the impact of realistic experimental errors. We then discuss the wide-ranging applications of these states for quantum technologies, including resource states in linear optical quantum computing, entanglement swapping for repeater networks, fundamental physics, and quantum metrology.

quant-ph↗

arXiv2024

Controlled dissipation for Rydberg atom experiments

We demonstrate a simple technique for adding controlled dissipation to Rydberg atom experiments. In our experiments we excite cold rubidium atoms in a magneto-optical trap to $70$-S Rydberg states, whilst simultaneously inducing forced dissipation by resonantly coupling the Rydberg state to a hyperfine level of the short-lived $6$-P state. The resulting effective dissipation can be varied in strength and switched on and off during a single experimental cycle.

physics.atom-ph↗