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

Physical Review A

Entangling two separate photonic ququarts using linear optical elements

Osung Kwon, Young-Sik Ra, Hyang‐Tag Lim, Yong‐Su Kim, Yoon-Ho Kim

Published Dec 22, 2014• 2 citations
Publisher

Abstract

We report an experimental demonstration of entangling two separable photonic ququarts using linear optical elements. Each ququart is implemented by using the dichotomic spatial and polarization modes of a single photon. By interfering two independent ququarts at a polarizing beam splitter, we experimentally generate entangled ququarts.
DOI
10.1103/physreva.90.063830

Related papers

Generating entangled states of two ququarts using linear optical elements

So-Young Baek, Yoon Ho Kim

We propose linear optical schemes for generating entangled states of two ququarts (four-dimensional quantum systems) in which the single-ququart state is constructed with frequency-nondegenerate biphoton polarization states of spontaneous parametric down-conversion. We show explicitly that it is possible to generate various two-ququart entangled states by interfering two ququarts at a linear optical beam splitter (an ordinary 50-50 beam splitter, a polarizing beam splitter, or a dichroic beam splitter).

Physical Review A•Mar 29, 2007•14 citations

Generating entangled states of two ququarts using linear optical elements

So-Young Baek, Yoon-Ho Kim

We propose linear-optical schemes for generating entangled-states of two ququarts (four-dimensional quantum systems) in which single-ququart states are constructed with frequency-nondegenerate biphoton polarization states of spontaneous parametric down-conversion. The schemes require beamsplitters and coincidence post-selection.

International Conference on Quantum Information•Jan 1, 2007•0 citations

Generation of an entangled four-photonWstate

Xu‐Bo Zou, K. Pahlke, Wolfgang M. Mathis

We present a scheme to produce an entangled four-photon W state by using linear optical elements. The symmetrical setup of linear optical elements consists of four beam splitters, four polarization beam splitters, and four mirrors. A photon Einstein-Podolsky-Rosen pair and two single photons are required as the input modes. The projection on the W state can be made by a four-photon coincidence measurement. Further, we show that by means of a horizontally oriented polarizer in front of one detector, the W state of three photons can be generated.

arXiv:quant-ph/0202090•Physical Review A•Oct 22, 2002•113 citations

Generating entangled states of two ququarts using linear optical elements

So-Young Baek, Yoon-Ho Kim

Recently, quantum systems with D-dimensional bases states (D > 2) or quDits have attracted much attention in the context of fundamental tests of quantum theory and potential applications in quantum information. In this paper, we discuss several schemes for generating entangled states of two ququarts (four-dimensional quantum systems). The ququart in our scheme is based on frequency-nondegenerate biphoton states of spontaneous parametric down-conversion and we show how the entangled states between two ququarts can be generated with simple linear optical elements, such as an ordinary 50/50 beamsplitter, a polarizing beamsplitter, or a dichroic beamsplitter. We also show that our scheme is capable of generating postselection-free two-ququart entangled states efficiently.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Aug 31, 2006•0 citations

Linear Polarization-Based Entanglement of a Single Photon, 2-Qubit Spatial Mode System

Neha Chandran, Srimaye Peddinti

Quantum communications offers a revolutionary solution to future data security challenges. Photons, the building blocks of quantum communications, encode quantum information, such as polarization and momentum. We investigate the enhancement of communications protocols by treating the spatial modes of a single polarization-encoded photon as two separate qubits. In effect, we can recreate traditional 2-photon operations in an individual photon, improving the scability of quantum devices. To demonstrate the robustness of our approach, we created path entanglement between the spatial mode qubits in the polarization basis. By introducing a linear approach, we avoid low conversion efficiencies and spectral limitations associated with nonlinear processes like spontaneous parametric down conversion (SPDC). We explore extending the concept of two-photon Hong-Ou-Mandel (HOM) interference to demonstrate instinguishability between two spatial modes. Using the Python-based photonic quantum computing library Perceval, we leveraged a single photon source as the input, combined with beam splitters (BS), waveplates (WP), and polarizing beam splitters (PBS). The HOM effect is observed when both spatial modes bunch together at the port to form a photon coincidence. We used Perceval's Strong Linear Optical (SLOS) simulator to run 10,000 shots and measured equal probabilities at all four detectors, confirming consistent indistinguishability of the modes when the HWP is rotated$\pi/4$radians. Finally by parameterizing the equivalent circuit in Qiskit with angles from$[0,2\pi]$, we showed a clear violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality, more definitively indicating successful entanglement.

IEEE International Conference on Quantum Computing and Engineering (QCE)•Sep 15, 2024•0 citations

Single-photon two-qubit entangled states: preparation and measurement

Yoon-Ho Kim

We report an experimental implementation of deterministic preparation and measurement of single-photon two-qubit entangled states, in which the polarization and the spatial modes of a single-photon each represent a quantum bit. It is demonstrated that all four single-photon two-qubit entangled states (Bell states) can be easily prepared and measured deterministically using linear optical elements alone. We also discuss how this scheme can be used for implementing recently proposed single-photon two-qubit quantum cryptography.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Oct 19, 2004•1 citation
We propose linear optical schemes for generating entangled states of two ququarts (four-dimensional quantum systems) in which the single-ququart state is constructed with frequency-nondegenerate biphoton polarization states of spontaneous parametric down-conversion. We show explicitly that it is possible to generate various two-ququart entangled states by interfering two ququarts at a linear optical beam splitter (an ordinary 50-50 beam splitter, a polarizing beam splitter, or a dichroic beam splitter).
We present a scheme to produce an entangled four-photon W state by using linear optical elements. The symmetrical setup of linear optical elements consists of four beam splitters, four polarization beam splitters, and four mirrors. A photon Einstein-Podolsky-Rosen pair and two single photons are required as the input modes. The projection on the W state can be made by a four-photon coincidence measurement. Further, we show that by means of a horizontally oriented polarizer in front of one detector, the W state of three photons can be generated.
Recently, quantum systems with D-dimensional bases states (D > 2) or quDits have attracted much attention in the context of fundamental tests of quantum theory and potential applications in quantum information. In this paper, we discuss several schemes for generating entangled states of two ququarts (four-dimensional quantum systems). The ququart in our scheme is based on frequency-nondegenerate biphoton states of spontaneous parametric down-conversion and we show how the entangled states between two ququarts can be generated with simple linear optical elements, such as an ordinary 50/50 beamsplitter, a polarizing beamsplitter, or a dichroic beamsplitter. We also show that our scheme is capable of generating postselection-free two-ququart entangled states efficiently.
Quantum communications offers a revolutionary solution to future data security challenges. Photons, the building blocks of quantum communications, encode quantum information, such as polarization and momentum. We investigate the enhancement of communications protocols by treating the spatial modes of a single polarization-encoded photon as two separate qubits. In effect, we can recreate traditional 2-photon operations in an individual photon, improving the scability of quantum devices. To demonstrate the robustness of our approach, we created path entanglement between the spatial mode qubits in the polarization basis. By introducing a linear approach, we avoid low conversion efficiencies and spectral limitations associated with nonlinear processes like spontaneous parametric down conversion (SPDC). We explore extending the concept of two-photon Hong-Ou-Mandel (HOM) interference to demonstrate instinguishability between two spatial modes. Using the Python-based photonic quantum computing library Perceval, we leveraged a single photon source as the input, combined with beam splitters (BS), waveplates (WP), and polarizing beam splitters (PBS). The HOM effect is observed when both spatial modes bunch together at the port to form a photon coincidence. We used Perceval's Strong Linear Optical (SLOS) simulator to run 10,000 shots and measured equal probabilities at all four detectors, confirming consistent indistinguishability of the modes when the HWP is rotatedπ/4\pi/4π/4radians. Finally by parameterizing the equivalent circuit in Qiskit with angles from[0,2π][0,2\pi][0,2π], we showed a clear violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality, more definitively indicating successful entanglement.
We report an experimental implementation of deterministic preparation and measurement of single-photon two-qubit entangled states, in which the polarization and the spatial modes of a single-photon each represent a quantum bit. It is demonstrated that all four single-photon two-qubit entangled states (Bell states) can be easily prepared and measured deterministically using linear optical elements alone. We also discuss how this scheme can be used for implementing recently proposed single-photon two-qubit quantum cryptography.