arXiv subjects

Milica Banic

Publications and source records attributed to Milica Banic.

8 recordsLinked to original sources

arXiv2025

Photon triplets from integrated microrings: A path towards deterministic non-Gaussianity on a chip

We propose cascaded spontaneous four-wave mixing (SFWM) in microring resonators as a scalable and efficient approach for directly generating non-Gaussian states of light. Focusing on the well-understood "low-gain" regime, we demonstrate that triplet generation through cascaded SFWM can be achieved with high efficiency and favorable spectral characteristics using realistic microring sources in AlGaAs. The ability to achieve the generation of light in a single set of supermodes -- and the predicted accessibility of the "high-gain" regime at realistic pump powers -- makes this source a promising candidate as a direct and deterministic source of non-Gaussian light for photonic quantum information processing.

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arXiv2025

Strategies for generating separable photon triplets in waveguides and ring resonators

Photon triplet sources exhibit non-Gaussian features, a key property for applications in quantum computing and quantum information. However, spectral correlations can limit the performance and detection efficiency of these systems. Motivated by this observation, we present a theoretical analysis of the spectral properties of photon triplets generated through spontaneous third-order parametric down-conversion in photonic devices, and discuss strategies to quantify and minimize such correlations. We propose two approaches: dispersion engineering in waveguides and pump engineering in resonators. We apply these strategies in two realistic source designs, namely a high-index-contrast optical fiber and a silicon nitride microring resonator. Finally, we discuss detection strategies for probing non-Gaussian features of the triplet state. We find that it is feasible to achieve few-mode generation of photon triplets using state-of-the-art experimental systems, a crucial step toward practical applications of photon triplet sources in quantum technologies.

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arXiv2025

Exact simulation of realistic Gottesman-Kitaev-Preskill cluster states

We describe a method for simulating and characterizing realistic Gottesman-Kitaev-Preskill (GKP) cluster states, rooted in the representation of resource states in terms of sums of Gaussian distributions in phase space. We apply our method to study the generation of single-mode GKP states via cat state breeding, and the formation of multimode GKP cluster states via linear optical circuits and homodyne measurements. We characterize resource states by referring to expectation values of their stabilizers, and witness operators constructed from them. Our method reproduces the results of standard Fock-basis simulations, while being more efficient, and being applicable in a broader parameter space. We also comment on the validity of the heuristic Gaussian random noise (GRN) model, through comparisons with our exact simulations: We find discrepancies in the stabilizer expectation values when homodyne measurement is involved in cluster state preparation, yet we find a close agreement between the two approaches on average.

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arXiv2024

Photonic multipartite entanglement in discrete variables without arbitrary unitaries

We present an approach for designing sources of postselected multipartite states based on photon-pair sources. Our approach can be applied to arbitrary target states in different encoding schemes and physical platforms. It also allows one to limit the types of components to be used in the device, such that lossy or difficult-to-implement optical elements can be avoided. As an example, we apply this strategy to design a passive integrated source of frequency-bin-encoded high-dimensional GHZ states with a 10 kHz on-chip generation rate for picojoule pump pulses.

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arXiv2023

Integrated photonic sources of frequency-bin-encoded multipartite entangled states

We demonstrate that genuine multipartite entangled states can be generated using frequency bin encoding in integrated photonic platforms. We introduce a source of four-photon GHZ states, and a source of three-photon W states. We predict generation rates on the order of 10$^4$ Hz for a silicon microring source with milliwatt pump powers. These results, along with the versatility and scalability of integrated structures, identify this as a promising approach for the generation of higher-dimensional and larger entangled states.

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arXiv2022

Two strategies for modeling nonlinear optics in lossy integrated photonic structures

We present two complementary strategies for modeling nonlinear quantum optics in realistic integrated optical devices, where scattering loss is present. In the first strategy, we model scattering loss as an attenuation; in the second, we employ a Hamiltonian treatment that includes a mechanism for scattering loss, such as a `phantom waveguide.' These strategies can be applied to a broad range of structures and processes. As an example, we use these two approaches to model spontaneous four-wave mixing in (i) a ring-channel system and (ii) an add-drop system. Even for these well-understood systems, our strategies yield some novel results. We show the rates of photon pairs, broken pairs, and lost pairs and their dependence on system parameters. We show that the properties of lost and broken photon pairs in such structures can be related to those of the un-scattered photon pairs, which are relatively simple to measure.

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arXiv2022

Resonant and non-resonant integrated third order parametric down-conversion

Third order parametric down-conversion describes a class of nonlinear processes in which a pump photon can be down-converted into triplets of photons. It has been identified as a source of non-classical light, with capabilities beyond those offered by better-established processes such as spontaneous four-wave mixing. Here we discuss the implementation of TOPDC in integrated photonic systems. We derive equations for the rates of TOPDC in a non-resonant (waveguide) and resonant (microring) platform, such that the scaling with experimental parameters can be plainly seen. We find that generally non-resonant platforms should be pursued for spontaneous TOPDC (SpTOPDC), whereas resonant platforms are more suitable for stimulated TOPDC (StTOPDC). We present a sample calculation for TOPDC rates in sample systems with conservative and accessible parameters. We find that StTOPDC should be observable with the current fabrication technology, and that with some progress in the design of TOPDC platforms, integrated SpTOPDC too could be demonstrated in the near term.

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arXiv2022

Generation of Photon Pairs by Stimulated Emission in Ring Resonators

Third-order parametric down-conversion (TOPDC) describes a class of nonlinear interactions in which a pump photon is converted into a photon triplet. This process can occur spontaneously, or it can be stimulated by seeding fields. In the former case, one typically has the generation of non-Gaussian states of light. In the latter, the situation is more variegated, for stimulated TOPDC (StTOPDC) can be implemented in many ways, depending on the number and properties of the seeding fields. Here we show that StTOPDC can be exploited for the generation of quantum correlated photon pairs. We examine the peculiar features of this approach when compared with second-order spontaneous parametric down-conversion and spontaneous four-wave mixing. We model StTOPDC in a microring resonator, predicting observable generation rates in a microring engineered for third-harmonic generation. We conclude that if the experimental difficulties associated with implementing StTOPDC can be overcome, it may soon be possible to demonstrate this process in resonant integrated devices.

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