Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Epsilon-Near-Zero Quantum Networks

Larissa Vertchenko, Nika Akopian, Andrei V. Lavrinenko

Published Aug 13, 2018• 2 citations
OpenAlex

Abstract

Realization of an on-chip quantum network is a major goal in the field of integrated quantum photonics. A typical network scalable on-chip demands optical integration of single photon sources, optical circuitry and detectors for routing and processing of quantum information. Current solutions either notoriously experience considerable decoherence or suffer from extended footprint dimensions limiting their on-chip scaling. Here we propose and numerically demonstrate a robust on-chip quantum network based on an epsilon-near-zero (ENZ) material, whose dielectric function has the real part close to zero. We show that ENZ materials strongly protect quantum information against decoherence and losses during its propagation in the dense network. As an example, we model a feasible implementation of an ENZ network and demonstrate that quantum information can be reliably sent across a titanium nitride grid with a coherence length of 434 nm, operating at room temperature, which is more than 40 times larger than state-of-the-art plasmonic analogs. Our results can, therefore, enable practical realization of large multi-node quantum photonic networks and circuits on-a-chip.

Related papers

Multiqubit entanglement and quantum phase gates with epsilon-near-zero plasmonic waveguides

Ying Li, Christos Argyropoulos

Multiqubit entanglement is extremely important to perform truly secure quantum optical communication and computing operations. However, the efficient generation of long-range entanglement over extended time periods between multiple qubits randomly distributed in a photonic system remains an outstanding challenge. This constraint is mainly due to the detrimental effects of decoherence and dephasing. To alleviate this issue, we present engineered epsilon-near-zero (ENZ) nanostructures that can maximize the coherence of light–matter interactions at room temperature. We investigate a practical ENZ plasmonic waveguide system, which simultaneously achieves multiqubit entanglement in elongated distances, extended time periods, and, even more importantly, independent of the emitters' positions. More specifically, we present efficient transient entanglement between three and four optical qubits mediated by ENZ with results that can be easily generalized to an arbitrary number of emitters. The entanglement between multiple qubits is characterized by computing the negativity metric applied to the proposed nanophotonic ENZ configuration. The ENZ response is found to be substantially advantageous to boost the coherence between multiple emitters compared to alternative plasmonic waveguide schemes. Finally, the super-radiance collective emission response at the ENZ resonance is utilized to design a high fidelity two-qubit quantum phase gate that can be used in various emerging quantum computing applications.

arXiv:2111.05245•Applied Physics Letters•Nov 22, 2021•15 citations

Epsilon-near-zero plasmonic waveguides to achieve multi-qubit quantum entanglement

Ying Li, Christos Argyropoulos

Multi-qubit entanglement is of paramount importance to perform truly secure quantum optical communication operations. In this work, we present efficient long-range entanglement mediated by plasmonic waveguides operating at their cut-off frequency, where they exhibit an effective epsilon-near-zero (ENZ) response. Only the excited ENZ mode at plasmonic waveguides has a strong and homogeneous electric field distribution compared to different modes excited at groove and rod waveguides, resulting in an efficient two- and multi-qubit entanglement that can persist over extended time periods and long distances. Efficient multipartite entanglement from three equidistantly arranged two-level quantum emitters (qubits) inside the ENZ waveguide is also demonstrated by using three different multi-qubit entanglement criterions, i.e., pairwise concurrence, negativity, and genuine multipartite entanglement. The findings of this work stress the importance of ENZ plasmonic waveguides as an ideal nanophotonic platform to support efficient quantum optical effects.

Digest - IEEE Antennas and Propagation Society. International Symposium•Jul 5, 2020•1 citation

Quantum information processing in large-scale photonic networks

Reinier van der Meer

This thesis focuses on optical quantum information processing in two parts. The first part focuses on photonic hardware. Large-scale photonic experiments require the generation of many indistinguishable single photons simultaneously. Traditionally, such photons are generated by spontaneous parametric down-conversion (SPDC). However, the suitability of such sources to generate many photons. We have identified the maximum limits of how many photons SPDC sources can be made. A second requirement of large-scale quantum photonics is having a network with many optical modes while maintaining low optical loss. Such networks are currently lacking. Therefore we introduce the possibility to use a rough surface scatterer for a quantum advantage experiment. Although such a network is far from universal, it has many modes and low loss. Another approach is to use integrated quantum photonics, which is fully reconfigurable and is a promising way of scaling up to large systems in an industrial setting. We have characterized a programmable low-loss 12-mode silicon nitride (SiN). In the second part of the thesis, various proof-of-principle quantum experiments were performed on a 12 mode SiN integrated photonic chip. Firstly, it was shown that these networks can be used to simulate wave propagation through disordered networks. This unconventional approach allows for full experimental access and control to the physical process, which is essential for such experiments. Secondly, we introduced a semi-device independent witness protocol that can in-situ verify the indistinguishability of photons on the chip, which is an essential tool to have when the system size increases and can no longer be efficiently simulated classically. The last experiment is a quantum simulation where we show how a pure quantum state locally thermalizes in a closed system.

•Jan 11, 2022•0 citations

Long-range quantum entanglement in dielectric mu-near-zero metamaterials

Olivia Mello, Larissa Vertchenko, Seth Nelson +4 more

Abstract Entanglement is paramount in quantum information processing. Many quantum systems suffer from spatial decoherence in distances over a wavelength and cannot be sustained over short time periods due to dissipation. However, long range solutions are required for the development of quantum information processing on chip. Photonic reservoirs mediating the interactions between qubits and their environment are suggested. Recent research takes advantage of extended wavelength inside near-zero refractive index media to solve the long-range problem along with less sensitivity on the position of quantum emitters. However, those recent proposals use plasmonic epsilon near-zero waveguides that are intrinsically lossy. Here, we propose a fully dielectric platform, compatible with the Nitrogen Vacancy (NV) diamond centers on-chip technology, to drastically improve the range of entanglement over 17 free-space wavelengths, or approximatively 12.5 µm, using mu near-zero metamaterials. We evaluate transient and steady state concurrence demonstrating an order of magnitude enhancement compared to previous works. This is, to the best of our knowledge, the first time that such a long distance is reported using this strategy. Moreover, value of the zero time delay second order correlation function $${g}_{12}^{(2)}(0)$$ g 12 ( 2 ) ( 0 ) are provided, showing antibunching signature correlated with a high degree of concurrence.

arXiv:2504.19160•Light Science & Applications•Sep 3, 2025•4 citations

Qubit entanglement across ε -near-zero media

Svend‐Age Biehs, G. S. Agarwal

Currently, epsilon-near-zero (ENZ) materials have become important for controlling the propagation of light and enhancing by several orders of magnitude the Kerr and other nonlinearities. Given this advance it is important to examine the quantum electrodynamic processes and information tasks near ENZ materials. We study the entanglement between two two-level systems near ENZ materials and compare our results with the case where the ENZ material is replaced by a metal. It is shown that with ENZ materials substantial entanglement can be achieved over larger distances than for metal films. We show that this entanglement over large distances is due to the fact that one can not only have large emission rates but also large energy transmission rates at the epsilon-near-zero wavelength. This establishes the superiority of ENZ materials for studying processes specifically important for quantum information tasks.

arXiv:1707.00962•Physical Review A•Aug 9, 2017•29 citations

Integrated nanophotonics for the development of fully functional quantum circuits based on on-demand single-photon emitters

Sven Rodt, Stephan Reitzenstein

In recent years, research on integrated quantum circuits has developed rapidly and exciting results have been achieved. The overarching goal of this emerging research direction in the field of modern quantum technology is the scalable integration of quantum functionality on robust chips. Such chips can work independently of one another, but it is even more interesting to develop them modularly for integration into larger quantum networks, thereby linking quantum computation and quantum communication in the same framework. In this context, the ongoing development and further optimization of integrated quantum circuits aim, inter alia, to achieve a quantum advantage in the area of quantum computing and to pave the way for multipartite quantum networks. The functionality of such chips is essentially based on single-photon operations, such as interference at beam splitters in combination with phase shifters in the field of linear optical quantum computing and Bell-state measurements for entanglement swapping in long-distance quantum networks. While individual functionalities such as CNOT gates and more complex quantum computing operations such as boson sampling in a combination of waveguide chips and external photon sources and detectors were successfully demonstrated, the field is currently facing the major challenge of integrating all necessary components monolithically on chip in order to exploit the full potential of integrated quantum nanophotonics. The present Perspective discusses the status and the present challenges of integrated quantum nanophotonics based on on-demand single-photon emitters and gives an outlook on required developments to enter the next level of fully functional quantum circuits for photonic quantum technology.

APL Photonics•Jan 1, 2021•55 citations
Realization of an on-chip quantum network is a major goal in the field of integrated quantum photonics. A typical network scalable on-chip demands optical integration of single photon sources, optical circuitry and detectors for routing and processing of quantum information. Current solutions either notoriously experience considerable decoherence or suffer from extended footprint dimensions limiting their on-chip scaling. Here we propose and numerically demonstrate a robust on-chip quantum network based on an epsilon-near-zero (ENZ) material, whose dielectric function has the real part close to zero. We show that ENZ materials strongly protect quantum information against decoherence and losses during its propagation in the dense network. As an example, we model a feasible implementation of an ENZ network and demonstrate that quantum information can be reliably sent across a titanium nitride grid with a coherence length of 434 nm, operating at room temperature, which is more than 40 times larger than state-of-the-art plasmonic analogs. Our results can, therefore, enable practical realization of large multi-node quantum photonic networks and circuits on-a-chip.
Multiqubit entanglement is extremely important to perform truly secure quantum optical communication and computing operations. However, the efficient generation of long-range entanglement over extended time periods between multiple qubits randomly distributed in a photonic system remains an outstanding challenge. This constraint is mainly due to the detrimental effects of decoherence and dephasing. To alleviate this issue, we present engineered epsilon-near-zero (ENZ) nanostructures that can maximize the coherence of light–matter interactions at room temperature. We investigate a practical ENZ plasmonic waveguide system, which simultaneously achieves multiqubit entanglement in elongated distances, extended time periods, and, even more importantly, independent of the emitters' positions. More specifically, we present efficient transient entanglement between three and four optical qubits mediated by ENZ with results that can be easily generalized to an arbitrary number of emitters. The entanglement between multiple qubits is characterized by computing the negativity metric applied to the proposed nanophotonic ENZ configuration. The ENZ response is found to be substantially advantageous to boost the coherence between multiple emitters compared to alternative plasmonic waveguide schemes. Finally, the super-radiance collective emission response at the ENZ resonance is utilized to design a high fidelity two-qubit quantum phase gate that can be used in various emerging quantum computing applications.
Multi-qubit entanglement is of paramount importance to perform truly secure quantum optical communication operations. In this work, we present efficient long-range entanglement mediated by plasmonic waveguides operating at their cut-off frequency, where they exhibit an effective epsilon-near-zero (ENZ) response. Only the excited ENZ mode at plasmonic waveguides has a strong and homogeneous electric field distribution compared to different modes excited at groove and rod waveguides, resulting in an efficient two- and multi-qubit entanglement that can persist over extended time periods and long distances. Efficient multipartite entanglement from three equidistantly arranged two-level quantum emitters (qubits) inside the ENZ waveguide is also demonstrated by using three different multi-qubit entanglement criterions, i.e., pairwise concurrence, negativity, and genuine multipartite entanglement. The findings of this work stress the importance of ENZ plasmonic waveguides as an ideal nanophotonic platform to support efficient quantum optical effects.
This thesis focuses on optical quantum information processing in two parts. The first part focuses on photonic hardware. Large-scale photonic experiments require the generation of many indistinguishable single photons simultaneously. Traditionally, such photons are generated by spontaneous parametric down-conversion (SPDC). However, the suitability of such sources to generate many photons. We have identified the maximum limits of how many photons SPDC sources can be made. A second requirement of large-scale quantum photonics is having a network with many optical modes while maintaining low optical loss. Such networks are currently lacking. Therefore we introduce the possibility to use a rough surface scatterer for a quantum advantage experiment. Although such a network is far from universal, it has many modes and low loss. Another approach is to use integrated quantum photonics, which is fully reconfigurable and is a promising way of scaling up to large systems in an industrial setting. We have characterized a programmable low-loss 12-mode silicon nitride (SiN). In the second part of the thesis, various proof-of-principle quantum experiments were performed on a 12 mode SiN integrated photonic chip. Firstly, it was shown that these networks can be used to simulate wave propagation through disordered networks. This unconventional approach allows for full experimental access and control to the physical process, which is essential for such experiments. Secondly, we introduced a semi-device independent witness protocol that can in-situ verify the indistinguishability of photons on the chip, which is an essential tool to have when the system size increases and can no longer be efficiently simulated classically. The last experiment is a quantum simulation where we show how a pure quantum state locally thermalizes in a closed system.
Abstract Entanglement is paramount in quantum information processing. Many quantum systems suffer from spatial decoherence in distances over a wavelength and cannot be sustained over short time periods due to dissipation. However, long range solutions are required for the development of quantum information processing on chip. Photonic reservoirs mediating the interactions between qubits and their environment are suggested. Recent research takes advantage of extended wavelength inside near-zero refractive index media to solve the long-range problem along with less sensitivity on the position of quantum emitters. However, those recent proposals use plasmonic epsilon near-zero waveguides that are intrinsically lossy. Here, we propose a fully dielectric platform, compatible with the Nitrogen Vacancy (NV) diamond centers on-chip technology, to drastically improve the range of entanglement over 17 free-space wavelengths, or approximatively 12.5 µm, using mu near-zero metamaterials. We evaluate transient and steady state concurrence demonstrating an order of magnitude enhancement compared to previous works. This is, to the best of our knowledge, the first time that such a long distance is reported using this strategy. Moreover, value of the zero time delay second order correlation function g12(2)(0){g}_{12}^{(2)}(0)g12(2)​(0) g 12 ( 2 ) ( 0 ) are provided, showing antibunching signature correlated with a high degree of concurrence.
Currently, epsilon-near-zero (ENZ) materials have become important for controlling the propagation of light and enhancing by several orders of magnitude the Kerr and other nonlinearities. Given this advance it is important to examine the quantum electrodynamic processes and information tasks near ENZ materials. We study the entanglement between two two-level systems near ENZ materials and compare our results with the case where the ENZ material is replaced by a metal. It is shown that with ENZ materials substantial entanglement can be achieved over larger distances than for metal films. We show that this entanglement over large distances is due to the fact that one can not only have large emission rates but also large energy transmission rates at the epsilon-near-zero wavelength. This establishes the superiority of ENZ materials for studying processes specifically important for quantum information tasks.
In recent years, research on integrated quantum circuits has developed rapidly and exciting results have been achieved. The overarching goal of this emerging research direction in the field of modern quantum technology is the scalable integration of quantum functionality on robust chips. Such chips can work independently of one another, but it is even more interesting to develop them modularly for integration into larger quantum networks, thereby linking quantum computation and quantum communication in the same framework. In this context, the ongoing development and further optimization of integrated quantum circuits aim, inter alia, to achieve a quantum advantage in the area of quantum computing and to pave the way for multipartite quantum networks. The functionality of such chips is essentially based on single-photon operations, such as interference at beam splitters in combination with phase shifters in the field of linear optical quantum computing and Bell-state measurements for entanglement swapping in long-distance quantum networks. While individual functionalities such as CNOT gates and more complex quantum computing operations such as boson sampling in a combination of waveguide chips and external photon sources and detectors were successfully demonstrated, the field is currently facing the major challenge of integrating all necessary components monolithically on chip in order to exploit the full potential of integrated quantum nanophotonics. The present Perspective discusses the status and the present challenges of integrated quantum nanophotonics based on on-demand single-photon emitters and gives an outlook on required developments to enter the next level of fully functional quantum circuits for photonic quantum technology.