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

Advances in Photonics of Quantum Computing, Memory, and Communication

Parallel preparation of a set of arbitrary path-polarization hyperentangled states

Hussien Garalnaby, Salem F. Hegazy, Salah Hasab Elnaby

Published Mar 4, 2019• 0 citations
Publisher

Abstract

The simultaneous production of a set of arbitrary hyperentangled states is crucial for quantum machines running variant quantum protocols concurrently, like universal quantum computers and quantum communication hubs. We present an experimental method to prepare a set of arbitrary path-polarization hyperentangled states concurrently using non-collinear spontaneous parametric down-conversion (SPDC). A cascaded pair of type-I crystals are pumped by 405-nm diagonally-polarized beam to produce a noncollinear stream of photon pairs. Compensation crystals are inserted to correct for the angular slope of the relative phase of the produced polarization entangled state. The pathentangled states are created over four pairs of slits positioned at conjugate locations to the pump beam. The local relative-phases of the path and polarization states can be independently tailored by intercepting the SPDC emission by tiltable birefringent and glass plates. The amplitudes of the polarization states is controlled by the manipulation of the polarization state of the pump. Also, the amplitudes of the path states is accessed by translating the slits over the SPDC cone. Here, while a pure state describes the whole SPDC emission, the produced states can be deemed an independent set by avoiding paths balanced to less than the coherence-length.

DOI
10.1117/12.2510115

Related papers

Tunable spatial compensation for polarization entangled photons

Salem F. Hegazy, Salah S. A. Obayya

The polarization entangled state produced via spontaneous parametric downconversion (SPDC) has relativephase maps in frequency and momentum domains which give an almost complete picture about the distinguishability and purity loss in the conjugate time and space domains. We demonstrate experimentally the tunable compensation of directional relative-phase profile for entangled photons generated by two cascaded / crossed crystals and captured over ultra-wide spatial window. We use a phase-only spatial light modulator (SLM) programmable via a personal computer to flatten (or correct for) the spatial relative-phase profile and also to add on-demand spatial phase profile. A fast, yet accurate, technique is introduced for frequent relative-phase measurements based on the tilt angle of a quarter wave plate (QWP) acting on the diagonally polarized pump beam and nulling the relative-phase of the entangled state at that direction. Our experimental measurements verify previous theoretical models for tunable compensation of the polarization two-photon state produced by the cascaded crystals arrangement.

SPIE Conference on Nonlinear Optics and its Applications•May 14, 2018•1 citation

Generation of four-photon hyperentangled state using spontaneous parametric down-conversion source with the second-order term

Ying-Qiu He, Ding Dong, Peng Tao +2 more

Nowadays,the generation of multiphoton entangled states is almost realized by combining the coupled entangled photons emitted from spontaneous parametric down-conversion (SPDC) with the first-order term.In this case,one may focus mainly on the first-order term,and then avoid multipair emission events by restricting experimental parameters.On the other hand,for the higher-order terms in SPDC source,these emitted entangled photons have interesting features.For example,they are entangled maximally not only in photon number for the spatial modes,but also in polarization degree of freedom.In general,two photons,which are entangled in two or more degrees of freedom,are called hyperentangled pair of photons or hyperentangled state.We present a scheme to generate the four-photon hyperentangled state based on four indistinguishable photons emitted from SPDC source with the second-order term.Consider two SPDC sources with equal probability of emission of photons in respective spatial modes.With the passive linear optical devices,i.e., beam splitters,half wave plates,polarizing beam splitters,etc.,under the condition of registering a specified four-photon coincidence,we can obtain the four-photon hyperentangled state in which the photons are entangled in both polarization and spatial-mode degrees of freedom.Here,of course,for an arbitrary fourfold coincidence detection,one obtains a canonical four-photon Greenberger-Horne-Zeilinger (GHZ) state.Then we show the results of fourfold coincidence detections and the corresponding probabilities for the four-photon GHZ states,where the generation of the four-photon hyperentangled state is included as long as we are not to distinguish the two detectors located at the same locations. As a result,our scheme has two notable features.When we only consider the second-order emission,since it is not needed for us to distinguish between the two SPDC sources,the present scheme is simple and feasible.Also,based on the postselection with fourfold coincidence detection,our scheme is suitable for the normal first-order emission where we restrict the four photons emitted from the same source.In this sense,our scheme is efficient.In a word,we describe a method to generate the four-photon hyperentangled state with the second-order emission in SPDC source,which may contribute to the exploration of multipair entanglement with higher-order emissions from the SPDC source.

Acta Physica Sinica•Jan 1, 2018•2 citations

Non-collinear and non-degenerate polarization-entangled photon generation via concurrent type-I parametric downconversion in PPLN

Hugues Guillet de Chatellus, Alexander V. Sergienko, Bahaa E. A. Saleh +2 more

A periodically poled lithium niobate (PPLN) crystal has been used as an efficient source of non-collinearly generated polarization-entangled photon pairs at 810 and 1550 nm. The PPLN crystal was endowed with a specially designed poling pattern and the entangled photons were generated via the nonlinear optical process of spontaneous parametric down conversion (SPDC). A novel design based on overlapping two concurrent type-I quasi-phase-matching structures in a single PPLN crystals produced correlated pairs of alternatively polarized photons in largely separated spectral regions. The phase of the resulting two-photon state is directly linked to parameters of the nonlinear grating. Continuous tunability of the generated Bell state, from Phi(+) to Phi(-), has been demonstrated by translating a slightly wedged crystal perpendicular to the pump beam.

Optics Express•Oct 16, 2006•39 citations

Direct generation of multiphoton hyperentanglement

Peng Zhao, Jia‐Wei Ying, Meng-Ying Yang +7 more

Multiphoton hyperentangement is fundamental in optical quantum information processing. Existing theory and experiments usually focus on producing two-photon hyperentanglement and multiphoton entangled states encoded in a single degree of freedom. Multiphoton entangled states have until now relied on the outcome postselection, a procedure where only the measurement results corresponding to the desired state are considered. Such an approach severely limits the usefulness of the resulting entangled states. We present the protocols of direct production of three- and four-photon hyperentanglement and extend the approach to an arbitrary number of photons through a straightforward cascade of spontaneous parametric down-conversion (SPDC) sources. The generated multiphoton hyperentangled states are encoded in polarization-spatial modes and polarization-time bin degrees of freedom, respectively. Numerical calculation shows that if the average photon number $\ensuremath{\mu}$ is 1, the down-conversion efficiency is $7.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and the repetition frequency of the laser is ${10}^{9}$ Hz, the number of the generation of three-photon and four-photon hyperentanglement after cascading can reach about $5.78\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$ and $4.44\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ pairs per second, respectively. By eliminating the constraints of outcome postselection, our protocols may represent progresses for multiphoton hyperentangement generation and provide a pivotal role in future multiparty and high-capacity communication networks.

arXiv:2406.08790•Physical Review Applied•Jan 2, 2025•21 citations

Generation of path-polarization hyperentanglement using quasi-phase-matching in quasi-periodic nonlinear photonic crystal

Guangqiang He, Chengrui Zhu, Yao Jiang +3 more

A compact scheme for the generation of path-polarization entangled photon pairs is proposed by using a quasi-periodic nonlinear photonic crystal to simultaneously accomplish four spontaneous parametric down-conversion processes. Moreover, we report experimental scheme to measure the polarization entanglement and path entanglement separately and theoretically get numerical results that verify some predictions about the hyperentanglement. This method can be expanded for the generation of multi-partite and two-photon path-polarization hyperentanglement in a single quasi-periodic nonlinear photonic crystal structure. This compact quantum light source can be used as a significant ingredient in quantum information science.

Scientific Reports•Jul 4, 2017•5 citations

Hyperentangled photon sources in semiconductor waveguides

Dongpeng Kang, L. G. Helt, Sergei V. Zhukovsky +3 more

We propose and analyze the performance of a technique to generate mode and polarization hyperentangled photons in monolithic semiconductor waveguides using two concurrent type-II spontaneous parametric downconversion (SPDC) processes.These two SPDC processes are achieved by waveguide engineering which allows for simultaneous modal phase matching with the pump beam in a higher-order mode.Paired photons generated in each process are cross polarized and guided by different guiding mechanisms, which produces entanglement in both polarization and spatial mode.Theoretical analysis shows that the output quantum state has a high quality of hyperentanglement by spectral filtering with a bandwidth of a few nanometers, while off-chip compensation is not needed.This technique offers a path to realize an electrically pumped hyperentangled photon source.

Physical Review A•Feb 19, 2014•24 citations
The simultaneous production of a set of arbitrary hyperentangled states is crucial for quantum machines running variant quantum protocols concurrently, like universal quantum computers and quantum communication hubs. We present an experimental method to prepare a set of arbitrary path-polarization hyperentangled states concurrently using non-collinear spontaneous parametric down-conversion (SPDC). A cascaded pair of type-I crystals are pumped by 405-nm diagonally-polarized beam to produce a noncollinear stream of photon pairs. Compensation crystals are inserted to correct for the angular slope of the relative phase of the produced polarization entangled state. The pathentangled states are created over four pairs of slits positioned at conjugate locations to the pump beam. The local relative-phases of the path and polarization states can be independently tailored by intercepting the SPDC emission by tiltable birefringent and glass plates. The amplitudes of the polarization states is controlled by the manipulation of the polarization state of the pump. Also, the amplitudes of the path states is accessed by translating the slits over the SPDC cone. Here, while a pure state describes the whole SPDC emission, the produced states can be deemed an independent set by avoiding paths balanced to less than the coherence-length.
The polarization entangled state produced via spontaneous parametric downconversion (SPDC) has relativephase maps in frequency and momentum domains which give an almost complete picture about the distinguishability and purity loss in the conjugate time and space domains. We demonstrate experimentally the tunable compensation of directional relative-phase profile for entangled photons generated by two cascaded / crossed crystals and captured over ultra-wide spatial window. We use a phase-only spatial light modulator (SLM) programmable via a personal computer to flatten (or correct for) the spatial relative-phase profile and also to add on-demand spatial phase profile. A fast, yet accurate, technique is introduced for frequent relative-phase measurements based on the tilt angle of a quarter wave plate (QWP) acting on the diagonally polarized pump beam and nulling the relative-phase of the entangled state at that direction. Our experimental measurements verify previous theoretical models for tunable compensation of the polarization two-photon state produced by the cascaded crystals arrangement.
Nowadays,the generation of multiphoton entangled states is almost realized by combining the coupled entangled photons emitted from spontaneous parametric down-conversion (SPDC) with the first-order term.In this case,one may focus mainly on the first-order term,and then avoid multipair emission events by restricting experimental parameters.On the other hand,for the higher-order terms in SPDC source,these emitted entangled photons have interesting features.For example,they are entangled maximally not only in photon number for the spatial modes,but also in polarization degree of freedom.In general,two photons,which are entangled in two or more degrees of freedom,are called hyperentangled pair of photons or hyperentangled state.We present a scheme to generate the four-photon hyperentangled state based on four indistinguishable photons emitted from SPDC source with the second-order term.Consider two SPDC sources with equal probability of emission of photons in respective spatial modes.With the passive linear optical devices,i.e., beam splitters,half wave plates,polarizing beam splitters,etc.,under the condition of registering a specified four-photon coincidence,we can obtain the four-photon hyperentangled state in which the photons are entangled in both polarization and spatial-mode degrees of freedom.Here,of course,for an arbitrary fourfold coincidence detection,one obtains a canonical four-photon Greenberger-Horne-Zeilinger (GHZ) state.Then we show the results of fourfold coincidence detections and the corresponding probabilities for the four-photon GHZ states,where the generation of the four-photon hyperentangled state is included as long as we are not to distinguish the two detectors located at the same locations. As a result,our scheme has two notable features.When we only consider the second-order emission,since it is not needed for us to distinguish between the two SPDC sources,the present scheme is simple and feasible.Also,based on the postselection with fourfold coincidence detection,our scheme is suitable for the normal first-order emission where we restrict the four photons emitted from the same source.In this sense,our scheme is efficient.In a word,we describe a method to generate the four-photon hyperentangled state with the second-order emission in SPDC source,which may contribute to the exploration of multipair entanglement with higher-order emissions from the SPDC source.
A periodically poled lithium niobate (PPLN) crystal has been used as an efficient source of non-collinearly generated polarization-entangled photon pairs at 810 and 1550 nm. The PPLN crystal was endowed with a specially designed poling pattern and the entangled photons were generated via the nonlinear optical process of spontaneous parametric down conversion (SPDC). A novel design based on overlapping two concurrent type-I quasi-phase-matching structures in a single PPLN crystals produced correlated pairs of alternatively polarized photons in largely separated spectral regions. The phase of the resulting two-photon state is directly linked to parameters of the nonlinear grating. Continuous tunability of the generated Bell state, from Phi(+) to Phi(-), has been demonstrated by translating a slightly wedged crystal perpendicular to the pump beam.
Multiphoton hyperentangement is fundamental in optical quantum information processing. Existing theory and experiments usually focus on producing two-photon hyperentanglement and multiphoton entangled states encoded in a single degree of freedom. Multiphoton entangled states have until now relied on the outcome postselection, a procedure where only the measurement results corresponding to the desired state are considered. Such an approach severely limits the usefulness of the resulting entangled states. We present the protocols of direct production of three- and four-photon hyperentanglement and extend the approach to an arbitrary number of photons through a straightforward cascade of spontaneous parametric down-conversion (SPDC) sources. The generated multiphoton hyperentangled states are encoded in polarization-spatial modes and polarization-time bin degrees of freedom, respectively. Numerical calculation shows that if the average photon number $\ensuremath{\mu}$ is 1, the down-conversion efficiency is $7.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and the repetition frequency of the laser is 109{10}^{9}109 Hz, the number of the generation of three-photon and four-photon hyperentanglement after cascading can reach about $5.78\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$ and $4.44\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ pairs per second, respectively. By eliminating the constraints of outcome postselection, our protocols may represent progresses for multiphoton hyperentangement generation and provide a pivotal role in future multiparty and high-capacity communication networks.
A compact scheme for the generation of path-polarization entangled photon pairs is proposed by using a quasi-periodic nonlinear photonic crystal to simultaneously accomplish four spontaneous parametric down-conversion processes. Moreover, we report experimental scheme to measure the polarization entanglement and path entanglement separately and theoretically get numerical results that verify some predictions about the hyperentanglement. This method can be expanded for the generation of multi-partite and two-photon path-polarization hyperentanglement in a single quasi-periodic nonlinear photonic crystal structure. This compact quantum light source can be used as a significant ingredient in quantum information science.
We propose and analyze the performance of a technique to generate mode and polarization hyperentangled photons in monolithic semiconductor waveguides using two concurrent type-II spontaneous parametric downconversion (SPDC) processes.These two SPDC processes are achieved by waveguide engineering which allows for simultaneous modal phase matching with the pump beam in a higher-order mode.Paired photons generated in each process are cross polarized and guided by different guiding mechanisms, which produces entanglement in both polarization and spatial mode.Theoretical analysis shows that the output quantum state has a high quality of hyperentanglement by spectral filtering with a bandwidth of a few nanometers, while off-chip compensation is not needed.This technique offers a path to realize an electrically pumped hyperentangled photon source.