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

arXiv:1912.07460 · Optics Letters

Quantum statistical signature of $ {\cal P}{\cal T} $PT symmetry breaking

Stefano Longhi

Published Feb 14, 2020• 24 citations
arXivHTMLPDF

Abstract

In multiparticle quantum interference, bosons show rather generally the tendency to bunch together, while fermions cannot. This behavior, which is rooted in the different statistics of the particles, results in a higher coincidence rate P for fermions than for bosons, i.e., P ( b o s ) < P ( f e r m ) . However, in lossy systems, such a general rule can be violated because bosons can avoid lossy regions. Here it is shown that, in a rather general optical system showing passive parity–time ( P T ) symmetry, at the P T symmetry breaking phase transition point, the coincidence probabilities for bosons and fermions are equalized, while in the broken P T phase, the reversal P ( b o s ) > P ( f e r m ) is observed. Such effect is exemplified by considering the passive P T -symmetric optical directional coupler.

DOI
10.1364/ol.386232

Related papers

Quantum interference in anti-parity-time symmetric coupled waveguide system

Yan Qin, Haixia Chen, Dajin Luo +4 more

We theoretically demonstrate quantum interference in an anti-parity-time (anti-PT) symmetric system based on coupled waveguides. We calculate the coincidence probability in an input polarization-entangled two-photon state, which can be used to simulate different statistical particles. When the birefringence of the waveguides is negligible, our results indicate that the coincidence probabilities of the bosons and fermions decrease exponentially with the propagation distance in both the unbroken and broken anti-PT symmetry regions owing to the dissipation. Particularly, loss-induced transparency is observed for the bosons. Simultaneously, the statistical rule valid in the Hermitian system is violated and the antibunching of bosons is observed. When the birefringence of the waveguides is considered, the coincidence probability of the bosons and fermions is equalized at the exceptional point (EP), whereas that of the bosons is less(greater) than that of the fermions in the broken(unbroken) anti-PT symmetry region. Additionally, we observe the Hong-Ou-Mandel dip for bosons in the broken anti-PT phase. Our research provides a complementary technique for the manipulation of quantum interference compared with the PT symmetric system and may be applied in building quantum devices with anti-PT symmetric quantum mechanics.

Optics Express•Aug 18, 2021•16 citations

Scanning Quantum Interference Across the Unbroken PT-Symmetric Phase

Friederike Klauck, Tom A. W. Wolterink, Matthias Heinrich +1 more

With their conceptual description of Parity-Time symmetry in 1998 [1], Bender and Boettcher inaugurated a new field of studies with fascinating implications on topology [2] and exceptional point dynamics [3], to name a few. Typically, PT-symmetric Hamiltonians exhibit real eigenvalues below a certain threshold, whereas above, the PT-symmetry is spontaneously broken as the eigenvalue spectrum becomes complex. Entirely passive configurations based solely on differential losses [7] allow the physics of PT symmetry to be carried over to a quantum-optical context [6] and explored therein [4]. Here we study the ways in which the degree of loss systematically impacts the characteristics of quantum correlations between interfering photons by analyzing the two-photon correlations in PT-symmetric directional couplers.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 26, 2023•0 citations

Observing PT-Symmetry Breaking in Integrated Quantum Photonics

Friederike Klauck, Matthias Heinrich, Alexander Szameit +1 more

In PT-symmetric systems, losses dramatically alter quantum correlations of interfering photons. We study the impact of increased loss on two-photon correlations in lossy couplers and observe changes in Hong-Ou-Mandel interference upon entering the PT-broken phase.

Quantum 2.0 Conference and Exhibition•Jan 1, 2024•0 citations

Interaction effects on the PT -symmetry-breaking transition in atomic gases

Ziheng Zhou, Zhenhua Yu

Non-Hermitian systems having parity-time ($\mathcal{PT}$) symmetry can undergo a transition, spontaneously breaking the symmetry. Ultracold atomic gases provide an ideal platform to study interaction effects on the transition. We consider a model system of $N$ bosons of two components confined in a tight trap. Radio-frequency and laser fields are coupled to the bosons such that the single-particle Non-Hermitian Hamiltonian ${h}_{\mathcal{P}T}=\ensuremath{-}i\mathrm{\ensuremath{\Gamma}}{\ensuremath{\sigma}}_{z}+J{\ensuremath{\sigma}}_{x}$, which has $\mathcal{PT}$ symmetry, can be simulated in a passive way, namely, in the physical system there is only incurred atom loss but no gain. We show that when interatomic interactions are tuned to maintain the symmetry, the $\mathcal{PT}$-symmetry-breaking transition is affected only by the SU(2) variant part of the interatomic interactions. We find that the transition point ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{tr}}$ decreases as the strength of this interaction part or $N$ increases; in the strong strength limit for this interaction part, ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{tr}}$ scales as the strength to the power of $\ensuremath{-}(N\ensuremath{-}1)$. We also give signatures of the $\mathcal{PT}$-symmetric and the symmetry-breaking phases for the interacting bosons in experiment.

arXiv:1901.01174•Physical Review A•Apr 10, 2019•22 citations

Anti-Hong-Ou-Mandel interference by coherent perfect absorption of entangled photons

Anton N. Vetlugin, Ruixiang Guo, Cesare Soci +1 more

Two-photon interference, known as the Hong-Ou-Mandel effect, has colossal implications for quantum technology. It was observed in 1987 with two photodetectors monitoring outputs of the beamsplitter illuminated by photon pairs: the coincidence rate of the detectors drops to zero when detected photons overlap in time. More broadly, bosons (e.g., photons) coalesce while fermions (e.g., electrons) anti-coalesce when interfering on a lossless beamsplitter. Quantum interference of bosons and fermions can be tested in a single - photonics platform, where bosonic and fermionic states are artificially created as pairs of entangled photons with symmetric and anti-symmetric spatial wavefunctions. We observed that interference on a lossy beamsplitter, or a subwavelength coherent absorber reverses quantum interference in such a way that bosonic states anti-coalesce while fermionic states exhibit coalescent-like behavior. The ability to generate states of light with different statistics and manipulate their interference offers important opportunities for quantum information and metrology.

arXiv:2105.05444•May 12, 2021•4 citations

Observation of PT symmetry breaking in two-photon correlations

Friederike Klauck, Matthias Heinrich, Alexander Szameit

We experimentally study the influence of PT-symmetry breaking on two-photon correlations in quasi-PT-symmetric couplers. While quantum interference is faithfully preserved in the unbroken phase. a characteristic rise of off-diagonal terms occurs beyond the exceptional point.

Conference on Lasers and Electro-Optics•Jan 1, 2021•0 citations
In multiparticle quantum interference, bosons show rather generally the tendency to bunch together, while fermions cannot. This behavior, which is rooted in the different statistics of the particles, results in a higher coincidence rate P for fermions than for bosons, i.e., P ( b o s ) < P ( f e r m ) . However, in lossy systems, such a general rule can be violated because bosons can avoid lossy regions. Here it is shown that, in a rather general optical system showing passive parity–time ( P T ) symmetry, at the P T symmetry breaking phase transition point, the coincidence probabilities for bosons and fermions are equalized, while in the broken P T phase, the reversal P ( b o s ) > P ( f e r m ) is observed. Such effect is exemplified by considering the passive P T -symmetric optical directional coupler.
We theoretically demonstrate quantum interference in an anti-parity-time (anti-PT) symmetric system based on coupled waveguides. We calculate the coincidence probability in an input polarization-entangled two-photon state, which can be used to simulate different statistical particles. When the birefringence of the waveguides is negligible, our results indicate that the coincidence probabilities of the bosons and fermions decrease exponentially with the propagation distance in both the unbroken and broken anti-PT symmetry regions owing to the dissipation. Particularly, loss-induced transparency is observed for the bosons. Simultaneously, the statistical rule valid in the Hermitian system is violated and the antibunching of bosons is observed. When the birefringence of the waveguides is considered, the coincidence probability of the bosons and fermions is equalized at the exceptional point (EP), whereas that of the bosons is less(greater) than that of the fermions in the broken(unbroken) anti-PT symmetry region. Additionally, we observe the Hong-Ou-Mandel dip for bosons in the broken anti-PT phase. Our research provides a complementary technique for the manipulation of quantum interference compared with the PT symmetric system and may be applied in building quantum devices with anti-PT symmetric quantum mechanics.
With their conceptual description of Parity-Time symmetry in 1998 [1], Bender and Boettcher inaugurated a new field of studies with fascinating implications on topology [2] and exceptional point dynamics [3], to name a few. Typically, PT-symmetric Hamiltonians exhibit real eigenvalues below a certain threshold, whereas above, the PT-symmetry is spontaneously broken as the eigenvalue spectrum becomes complex. Entirely passive configurations based solely on differential losses [7] allow the physics of PT symmetry to be carried over to a quantum-optical context [6] and explored therein [4]. Here we study the ways in which the degree of loss systematically impacts the characteristics of quantum correlations between interfering photons by analyzing the two-photon correlations in PT-symmetric directional couplers.
Non-Hermitian systems having parity-time (PT\mathcal{PT}PT) symmetry can undergo a transition, spontaneously breaking the symmetry. Ultracold atomic gases provide an ideal platform to study interaction effects on the transition. We consider a model system of NNN bosons of two components confined in a tight trap. Radio-frequency and laser fields are coupled to the bosons such that the single-particle Non-Hermitian Hamiltonian ${h}_{\mathcal{P}T}=\ensuremath{-}i\mathrm{\ensuremath{\Gamma}}{\ensuremath{\sigma}}_{z}+J{\ensuremath{\sigma}}_{x}$, which has PT\mathcal{PT}PT symmetry, can be simulated in a passive way, namely, in the physical system there is only incurred atom loss but no gain. We show that when interatomic interactions are tuned to maintain the symmetry, the PT\mathcal{PT}PT-symmetry-breaking transition is affected only by the SU(2) variant part of the interatomic interactions. We find that the transition point ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{tr}}$ decreases as the strength of this interaction part or NNN increases; in the strong strength limit for this interaction part, ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{tr}}$ scales as the strength to the power of $\ensuremath{-}(N\ensuremath{-}1)$. We also give signatures of the PT\mathcal{PT}PT-symmetric and the symmetry-breaking phases for the interacting bosons in experiment.
Two-photon interference, known as the Hong-Ou-Mandel effect, has colossal implications for quantum technology. It was observed in 1987 with two photodetectors monitoring outputs of the beamsplitter illuminated by photon pairs: the coincidence rate of the detectors drops to zero when detected photons overlap in time. More broadly, bosons (e.g., photons) coalesce while fermions (e.g., electrons) anti-coalesce when interfering on a lossless beamsplitter. Quantum interference of bosons and fermions can be tested in a single - photonics platform, where bosonic and fermionic states are artificially created as pairs of entangled photons with symmetric and anti-symmetric spatial wavefunctions. We observed that interference on a lossy beamsplitter, or a subwavelength coherent absorber reverses quantum interference in such a way that bosonic states anti-coalesce while fermionic states exhibit coalescent-like behavior. The ability to generate states of light with different statistics and manipulate their interference offers important opportunities for quantum information and metrology.