arxiv: 2604.23550 · v1 · submitted 2026-04-26 · 🪐 quant-ph · physics.optics

Recognition: unknown

Observation of OAM non-conservation in entangled photon generation

Suman Karan , Anand K. Jha

Authors on Pith no claims yet

Pith reviewed 2026-05-08 06:21 UTC · model grok-4.3

classification 🪐 quant-ph physics.optics

keywords orbital angular momentumOAM conservationType-I SPDCentangled photonsspatial walk-offspontaneous parametric down-conversiontwo-photon detection

0 comments

The pith

OAM is not conserved in Type-I SPDC due to spatial walk-off in the crystal.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper challenges the standard view that orbital angular momentum is conserved in Type-I spontaneous parametric down-conversion used to generate entangled photon pairs. Using a new high-sensitivity two-photon OAM detector, the authors directly observe non-conservation in Type-I SPDC, which prior theory and experiments had treated as conserved. They attribute the effect to spatial walk-off inside the nonlinear crystal and derive it from a calculation that avoids the usual phase-matching approximations. This matters because many methods for creating high-dimensional OAM entanglement rest on the conservation assumption, and its failure changes how those states must be prepared and analyzed. If the result holds, it requires updating both the theoretical models and the experimental protocols for OAM-based quantum technologies.

Core claim

Contrary to the current understanding that OAM is conserved in Type-I SPDC, the authors report experimental non-conservation of OAM in Type-I SPDC. They demonstrate this with a high-sensitivity two-photon OAM detector and attribute the non-conservation to the spatial walk-off effect. The attribution is supported by a theoretical framework that does not rely on standard phase-matching approximations.

What carries the argument

High-sensitivity two-photon OAM detector that measures joint OAM values directly, combined with a spatial walk-off model derived without phase-matching approximations.

If this is right

Generation of high-dimensional OAM-entangled states via Type-I SPDC must incorporate non-conservation rather than assume conservation.
Foundational models of OAM in parametric down-conversion require revision to include walk-off effects in Type-I processes.
High-sensitivity two-photon OAM detectors enable resolution of other open questions about conservation laws in SPDC.
Quantum information protocols that rely on OAM entanglement from Type-I sources will need adjusted state preparation and verification steps.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Controlling crystal orientation or pump geometry to minimize walk-off could be tested as a way to restore apparent conservation for specific applications.
The same non-conservation might appear in other nonlinear processes once measured with detectors of comparable sensitivity.
Calibration routines for future OAM-based quantum devices may need to include walk-off corrections derived from the phase-matching-free framework.

Load-bearing premise

The new two-photon OAM detector accurately records true OAM values without calibration biases or artifacts that could create the appearance of non-conservation.

What would settle it

An independent measurement with a different OAM detection method that shows perfect OAM conservation in the same Type-I SPDC setup, or a full phase-matching calculation that recovers conservation even after including walk-off.

read the original abstract

Orbital angular momentum (OAM)-entangled states produced by spontaneous parametric down-conversion (SPDC) are considered ideal for realizing high-dimensional entangled states, which have several advantages for quantum technologies. However, the limited sensitivity of current two-photon OAM detectors is a major roadblock not only for realizing such technologies but also for resolving foundational questions, such as OAM conservation in SPDC. The current theoretical understanding is that OAM is not conserved in Type-II SPDC but is conserved in Type-I. Experimentally, although non-conservation in TypeII has not been demonstrated, conservation in Type-I has been reported frequently and has become an underlying assumption for techniques generating high-dimensional OAM entangled states. In this work, we experimentally demonstrate a high-sensitivity two-photon OAM detector, using which, contrary to the current understanding, we report non-conservation of OAM in Type-I SPDC. We attribute this to a spatial walk-off effect and prove it using a framework free of standard phase-matching approximations.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The observation of OAM non-conservation in Type-I SPDC stands on the unverified accuracy of the authors' new two-photon detector.

read the letter

The paper claims to have observed non-conservation of orbital angular momentum in Type-I spontaneous parametric down-conversion, which has been taken as conserved in prior work. They did this with a new high-sensitivity two-photon OAM detector and attribute the effect to spatial walk-off, supported by a theoretical framework that avoids standard phase-matching approximations. What the paper does well is introduce this detector and the approximation-free approach. The detector seems key to accessing the effect that previous measurements missed. The theory part shows an effort to model the system more accurately than usual. The soft spots are around the experimental validation. The central result depends on the detector correctly assigning OAM values. There is no mention of calibration against known cases where conservation holds, such as certain configurations with zero walk-off or independent measurements. If the detector has unaccounted biases from the walk-off or mode efficiencies, the non-conservation could be instrumental rather than physical. The abstract does not provide quantitative details on this, which leaves the claim open to the concern that the detector response mimics the violation. Overall, this is aimed at researchers in quantum optics and quantum information who rely on OAM entanglement. It could be useful for those thinking about conservation laws or building better detectors. The paper has enough new elements to warrant a serious referee, who can examine the full data, error bars, and detector characterization. I recommend sending it for peer review rather than desk rejecting it, because the topic is foundational and the approach is novel enough to deserve expert scrutiny.

Referee Report

1 major / 0 minor

Summary. The manuscript reports the development of a high-sensitivity two-photon OAM detector and its application to experimentally demonstrate non-conservation of orbital angular momentum (OAM) in Type-I spontaneous parametric down-conversion (SPDC). This observation contradicts the prevailing theoretical and experimental consensus that OAM is conserved in Type-I SPDC. The authors attribute the apparent violation to spatial walk-off and support the result with a theoretical framework that avoids standard phase-matching approximations.

Significance. If the central experimental claim holds after rigorous validation, the work would be significant for quantum optics and quantum information, as it challenges a foundational assumption underlying many OAM-entangled photon sources and high-dimensional entanglement protocols. The high-sensitivity two-photon detector and the approximation-free walk-off framework represent clear technical advances that could enable new experiments if the non-conservation result is confirmed to be physical rather than instrumental.

major comments (1)

The non-conservation result is obtained exclusively with the authors' new two-photon OAM detector. No quantitative calibration data or cross-checks against a known OAM-conserving reference (such as a collinear Type-I SPDC configuration with verified zero walk-off or independent SLM-based sorting) are presented, leaving open the possibility that mode-dependent efficiency, cross-talk, or walk-off-induced bias in the detector could produce the apparent violation. This validation is load-bearing for the central claim.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their thorough review and for highlighting the importance of rigorous detector validation, which is indeed central to our claims. We address the major comment below and will incorporate the requested clarifications and data in the revised manuscript.

read point-by-point responses

Referee: The non-conservation result is obtained exclusively with the authors' new two-photon OAM detector. No quantitative calibration data or cross-checks against a known OAM-conserving reference (such as a collinear Type-I SPDC configuration with verified zero walk-off or independent SLM-based sorting) are presented, leaving open the possibility that mode-dependent efficiency, cross-talk, or walk-off-induced bias in the detector could produce the apparent violation. This validation is load-bearing for the central claim.

Authors: We agree that quantitative calibration and independent cross-checks are essential to substantiate the central claim. The manuscript describes the detector architecture and its operating principle in detail, but we acknowledge that more explicit quantitative benchmarks against reference configurations were not included. In the revised version we will add a new subsection presenting (i) measured mode-dependent detection efficiencies and cross-talk matrices for OAM modes up to |ℓ|=5, (ii) a direct comparison of the same Type-I SPDC source measured with the new detector versus a conventional SLM-based projective sorter, and (iii) data from a collinear Type-I geometry with minimized walk-off in which OAM conservation is recovered to within experimental uncertainty. These additions will demonstrate that the observed non-conservation is not an artifact of the detector and will be accompanied by the corresponding raw coincidence histograms. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental result with independent framework

full rationale

The paper reports an experimental observation of OAM non-conservation in Type-I SPDC using a custom two-photon detector, attributes it to spatial walk-off, and supports the attribution via an approximation-free theoretical framework. No load-bearing step reduces by construction to a fitted parameter, self-definition, or self-citation chain; the central claim rests on measured data rather than a tautological derivation. The detector calibration and framework are presented as independent of the target non-conservation result, satisfying the criteria for a self-contained experimental finding.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review yields insufficient detail to enumerate specific free parameters, axioms, or invented entities; no explicit fitting parameters or new postulated entities are mentioned.

pith-pipeline@v0.9.0 · 5471 in / 1082 out tokens · 21777 ms · 2026-05-08T06:21:07.447671+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

59 extracted references · 50 canonical work pages

[1]

Wang,et al., Terabit free-space data transmission employing orbital angular momentum multiplexing.Nature Photonics6(7), 488–496 (2012), doi:10.1038/nphoton.2012.138

J. Wang,et al., Terabit free-space data transmission employing orbital angular momentum multiplexing.Nature Photonics6(7), 488–496 (2012), doi:10.1038/nphoton.2012.138

work page doi:10.1038/nphoton.2012.138 2012
[2]

Bozinovic,et al., Terabit-Scale Orbital Angular Momentum Mode Division Multiplexing in Fibers.Science340(6140), 1545–1548 (2013), doi:10.1126/science.1237861

N. Bozinovic,et al., Terabit-Scale Orbital Angular Momentum Mode Division Multiplexing in Fibers.Science340(6140), 1545–1548 (2013), doi:10.1126/science.1237861

work page doi:10.1126/science.1237861 2013
[3]

N. J. Cerf, M. Bourennane, A. Karlsson, N. Gisin, Security of Quantum Key Distribu- tion Usingd-Level Systems.Physical Review Letters88(12), 127902 (2002), doi:10.1103/ physrevlett.88.127902

2002
[4]

G. M. Nikolopoulos, K. S. Ranade, G. Alber, Error tolerance of two-basis quantum-key- distribution protocols using qudits and two-way classical communication.Physical Review A 73(3), 032325 (2006), doi:10.1103/physreva.73.032325

work page doi:10.1103/physreva.73.032325 2006
[5]

T. C. Ralph, K. J. Resch, A. Gilchrist, Efficient Toffoli Gates Using Qudits.Physical Review A 75(2), 022313 (2007), doi:10.1103/PhysRevA.75.022313

work page doi:10.1103/physreva.75.022313 2007
[6]

B. P. Lanyon,et al., Simplifying Quantum Logic Using Higher-Dimensional Hilbert Spaces. Nature Physics5(2), 134–140 (2009), doi:10.1038/nphys1150. 21

work page doi:10.1038/nphys1150 2009
[7]

D’ Ambrosio,et al., Photonic Polarization Gears for Ultra-Sensitive Angular Measurements

V. D’ Ambrosio,et al., Photonic Polarization Gears for Ultra-Sensitive Angular Measurements. Nature Communications4(1), 2432 (2013), doi:10.1038/ncomms3432

work page doi:10.1038/ncomms3432 2013
[9]

A. C. Dada, J. Leach, G. S. Buller, M. J. Padgett, E. Andersson, Experimental high-dimensional two-photon entanglement and violations of generalized Bell inequalities.Nature Physics7(9), 677–680 (2011), doi:10.1038/nphys1996

work page doi:10.1038/nphys1996 2011
[10]

C. K. Law, J. H. Eberly, Analysis and Interpretation of High Transverse Entanglement in Optical Parametric Down Conversion.Physical Review Letters92(12), 127903 (2004), doi: 10.1103/physrevlett.92.127903

work page doi:10.1103/physrevlett.92.127903 2004
[11]

F. M. Miatto, H. Di Lorenzo Pires, S. M. Barnett, M. P. van Exter, Spatial Schmidt modes generated in parametric down-conversion.The European Physical Journal D66(10) (2012), doi:10.1140/epjd/e2012-30035-3

work page doi:10.1140/epjd/e2012-30035-3 2012
[12]

D. N. Klyshko, Photons and Nonlinear Optics (2018), doi:10.1201/9780203743508

work page doi:10.1201/9780203743508 2018
[13]

R. W. Boyd,Nonlinear Optics, Third Edition(Academic Press, Inc., USA), 3rd ed. (2008)

2008
[14]

A. Mair, A. Vaziri, G. Weihs, A. Zeilinger, Entanglement of the orbital angular momentum states of photons.Nature412(6844), 313–316 (2001), doi:10.1038/35085529

work page doi:10.1038/35085529 2001
[15]

J. Arlt, K. Dholakia, L. Allen, M. J. Padgett, Parametric down-conversion for light beams possessing orbital angular momentum.Physical Review A59(5), 3950–3952 (1999), doi: 10.1103/physreva.59.3950

work page doi:10.1103/physreva.59.3950 1999
[16]

H. H. Arnaut, G. A. Barbosa, Orbital and Intrinsic Angular Momentum of Single Photons and Entangled Pairs of Photons Generated by Parametric Down-Conversion.Physical Review Letters85(2), 286–289 (2000), doi:10.1103/physrevlett.85.286. 22

work page doi:10.1103/physrevlett.85.286 2000
[17]

Karan, R

S. Karan, R. Prasad, A. K. Jha, Postselection-free controlled generation of a high-dimensional orbital-angular-momentum entangled state.Physical Review Applied20(5), 054027 (2023), doi:10.1103/physrevapplied.20.054027

work page doi:10.1103/physrevapplied.20.054027 2023
[18]

Vaziri, J.-W

A. Vaziri, J.-W. Pan, T. Jennewein, G. Weihs, A. Zeilinger, Concentration of Higher Dimen- sional Entanglement: Qutrits of Photon Orbital Angular Momentum.Physical Review Letters 91(22), 227902 (2003), doi:10.1103/physrevlett.91.227902

work page doi:10.1103/physrevlett.91.227902 2003
[19]

Wang,et al., Generation of the complete four-dimensional Bell basis.Optica4(12), 1462 (2017), doi:10.1364/optica.4.001462

F. Wang,et al., Generation of the complete four-dimensional Bell basis.Optica4(12), 1462 (2017), doi:10.1364/optica.4.001462

work page doi:10.1364/optica.4.001462 2017
[20]

Liu,et al., Multidimensional entanglement transport through single-mode fiber.Science Advances6(4) (2020), doi:10.1126/sciadv.aay0837

J. Liu,et al., Multidimensional entanglement transport through single-mode fiber.Science Advances6(4) (2020), doi:10.1126/sciadv.aay0837

work page doi:10.1126/sciadv.aay0837 2020
[21]

X. Qiu, H. Guo, L. Chen, Remote transport of high-dimensional orbital angular momentum states and ghost images via spatial-mode-engineered frequency conversion.Nature Communi- cations14(1) (2023), doi:10.1038/s41467-023-43950-4

work page doi:10.1038/s41467-023-43950-4 2023
[22]

Zhang,et al., Simultaneous entanglement swapping of multiple orbital angular momentum states of light.Nature Communications8(1) (2017), doi:10.1038/s41467-017-00706-1

Y. Zhang,et al., Simultaneous entanglement swapping of multiple orbital angular momentum states of light.Nature Communications8(1) (2017), doi:10.1038/s41467-017-00706-1

work page doi:10.1038/s41467-017-00706-1 2017
[23]

Bechmann-Pasquinucci, A

H. Bechmann-Pasquinucci, A. Peres, Quantum Cryptography with 3-State Systems.Physical Review Letters85(15), 3313–3316 (2000), doi:10.1103/physrevlett.85.3313

work page doi:10.1103/physrevlett.85.3313 2000
[24]

Ecker,et al., Overcoming Noise in Entanglement Distribution.Physical Review X9(4), 041042 (2019), doi:10.1103/physrevx.9.041042

S. Ecker,et al., Overcoming Noise in Entanglement Distribution.Physical Review X9(4), 041042 (2019), doi:10.1103/physrevx.9.041042

work page doi:10.1103/physrevx.9.041042 2019
[25]

Sit,et al., High-dimensional intracity quantum cryptography with structured photons.Optica 4(9), 1006 (2017), doi:10.1364/optica.4.001006

A. Sit,et al., High-dimensional intracity quantum cryptography with structured photons.Optica 4(9), 1006 (2017), doi:10.1364/optica.4.001006

work page doi:10.1364/optica.4.001006 2017
[26]

Bouchard,et al., Quantum cryptography with twisted photons through an outdoor underwater channel.Optics Express26(17), 22563 (2018), doi:10.1364/oe.26.022563

F. Bouchard,et al., Quantum cryptography with twisted photons through an outdoor underwater channel.Optics Express26(17), 22563 (2018), doi:10.1364/oe.26.022563

work page doi:10.1364/oe.26.022563 2018
[27]

Hu,et al., Beating the channel capacity limit for superdense coding with entangled ququarts.Science Advances4(7) (2018), doi:10.1126/sciadv.aat9304

X.-M. Hu,et al., Beating the channel capacity limit for superdense coding with entangled ququarts.Science Advances4(7) (2018), doi:10.1126/sciadv.aat9304. 23

work page doi:10.1126/sciadv.aat9304 2018
[28]

L. Chen, J. Lei, J. Romero, Quantum digital spiral imaging.Light: Science & Applications 3(3), e153–e153 (2014), doi:10.1038/lsa.2014.34

work page doi:10.1038/lsa.2014.34 2014
[30]

S. P. Walborn, A. N. de Oliveira, R. S. Thebaldi, C. H. Monken, Entanglement and conservation of orbital angular momentum in spontaneous parametric down-conversion.Physical Review A 69(2), 023811 (2004), doi:10.1103/physreva.69.023811

work page doi:10.1103/physreva.69.023811 2004
[31]

G. A. Barbosa, Transverse coincidence structures in spontaneous parametric down-conversion with orbital angular momentum: Theory.Physical Review A76(3), 033821 (2007), doi: 10.1103/physreva.76.033821

work page doi:10.1103/physreva.76.033821 2007
[32]

S. Feng, P. Kumar, Spatial Symmetry and Conservation of Orbital Angular Momentum in Spontaneous Parametric Down-Conversion.Physical Review Letters101(16), 163602 (2008), doi:10.1103/physrevlett.101.163602

work page doi:10.1103/physrevlett.101.163602 2008
[33]

M. H. Rubin, Transverse correlation in optical spontaneous parametric down-conversion.Phys- ical Review A54(6), 5349–5360 (1996), doi:10.1103/physreva.54.5349

work page doi:10.1103/physreva.54.5349 1996
[34]

Molina-Terriza, J

G. Molina-Terriza, J. P. Torres, L. Torner, Orbital angular momentum of photons in noncollinear parametric downconversion.Optics Communications228(1–3), 155–160 (2003), doi:10.1016/ j.optcom.2003.09.071

2003
[35]

H. Qassim,et al., Limitations to the determination of a Laguerre–Gauss spectrum via projective, phase-flattening measurement.Journal of the Optical Society of America B31(6), A20 (2014), doi:10.1364/josab.31.000a20

work page doi:10.1364/josab.31.000a20 2014
[36]

A. K. Jha,et al., Angular Two-Photon Interference and Angular Two-Qubit States.Physical Review Letters104(1), 010501 (2010), doi:10.1103/physrevlett.104.010501

work page doi:10.1103/physrevlett.104.010501 2010
[37]

Malik, S

M. Malik, S. Murugkar, J. Leach, R. W. Boyd, Measurement of the orbital-angular-momentum spectrum of fields with partial angular coherence using double-angular-slit interference.Phys- ical Review A—Atomic, Molecular, and Optical Physics86(6), 063806 (2012). 24

2012
[38]

Kulkarni, S

G. Kulkarni, S. Karan, A. K. Jha, Measurement of Pure States of Light in the Orbital-Angular- Momentum Basis Using Nine Multipixel Image Acquisitions.Physical Review Applied13(5), 054077 (2020), doi:10.1103/physrevapplied.13.054077

work page doi:10.1103/physrevapplied.13.054077 2020
[39]

Malik,et al., Direct measurement of a 27-dimensional orbital-angular-momentum state vector.Nature communications5(1), 3115 (2014)

M. Malik,et al., Direct measurement of a 27-dimensional orbital-angular-momentum state vector.Nature communications5(1), 3115 (2014)

2014
[40]

Kulkarni, R

G. Kulkarni, R. Sahu, O. S. Maga ˜na-Loaiza, R. W. Boyd, A. K. Jha, Single-shot measurement of the orbital-angular-momentum spectrum of light.Nature Communications8(1) (2017), doi:10.1038/s41467-017-01215-x

work page doi:10.1038/s41467-017-01215-x 2017
[41]

R. F. Offer, D. Stulga, E. Riis, S. Franke-Arnold, A. S. Arnold, Spiral bandwidth of four-wave mixing in Rb vapour.Communications Physics1(1) (2018), doi:10.1038/s42005-018-0077-5

work page doi:10.1038/s42005-018-0077-5 2018
[42]

Di Lorenzo Pires, H

H. Di Lorenzo Pires, H. C. B. Florijn, M. P. van Exter, Measurement of the Spiral Spectrum of Entangled Two-Photon States.Physical Review Letters104(2), 020505 (2010), doi:10.1103/ physrevlett.104.020505

2010
[43]

W. H. Peeters, E. J. K. Verstegen, M. P. van Exter, Orbital angular momentum analysis of high- dimensional entanglement.Physical Review A76(4), 042302 (2007), doi:10.1103/physreva. 76.042302

work page doi:10.1103/physreva 2007
[44]

D. Zia, N. Dehghan, A. D’Errico, F. Sciarrino, E. Karimi, Interferometric imaging of amplitude and phase of spatial biphoton states.Nature Photonics17(11), 1009–1016 (2023), doi:10.1038/ s41566-023-01272-3

2023
[45]

Dehghan, A

N. Dehghan, A. D’Errico, F. Di Colandrea, E. Karimi, Biphoton state reconstruction via phase retrieval methods.Optica11(8), 1115 (2024), doi:10.1364/optica.527661

work page doi:10.1364/optica.527661 2024
[46]

Ibarra-Borja,et al., Direct observation of OAM correlations from spatially entangled bi- photon states.Optics Express27(18), 25228 (2019), doi:10.1364/oe.27.025228

Z. Ibarra-Borja,et al., Direct observation of OAM correlations from spatially entangled bi- photon states.Optics Express27(18), 25228 (2019), doi:10.1364/oe.27.025228

work page doi:10.1364/oe.27.025228 2019
[47]

Final result of the ma- jorana demonstrator’s search for neutrinoless double-β decay in 76Ge (2023)

Y. Li,et al., Two-Measurement Tomography of High-Dimensional Orbital Angular Momentum Entanglement.Physical Review Letters130(5), 050805 (2023), doi:10.1103/physrevlett.130. 050805. 25

work page doi:10.1103/physrevlett.130 2023
[48]

Y. Xu, S. Choudhary, R. W. Boyd, Stimulated emission tomography for efficient charac- terization of spatial entanglement.Physical Review Research6(4), l042047 (2024), doi: 10.1103/physrevresearch.6.l042047

work page doi:10.1103/physrevresearch.6.l042047 2024
[49]

Karan, M

S. Karan, M. P. Van Exter, A. K. Jha, Broadband uniform-efficiency OAM-mode detector. Science Advances11(11) (2025), doi:10.1126/sciadv.adq7201

work page doi:10.1126/sciadv.adq7201 2025
[50]

Allen, M

L. Allen, M. W. Beijersbergen, R. J. C. Spreeuw, J. P. Woerdman, Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser modes.Physical Review A45(11), 8185–8189 (1992), doi:10.1103/physreva.45.8185

work page doi:10.1103/physreva.45.8185 1992
[51]

J. P. Torres, A. Alexandrescu, L. Torner, Quantum spiral bandwidth of entangled two-photon states.Physical Review A68(5), 050301 (2003), doi:10.1103/physreva.68.050301

work page doi:10.1103/physreva.68.050301 2003
[52]

F. M. Miatto, A. M. Yao, S. M. Barnett, Full characterization of the quantum spiral bandwidth of entangled biphotons.Physical Review A83(3), 033816 (2011), doi:10.1103/physreva.83. 033816

work page doi:10.1103/physreva.83 2011
[53]

Kulkarni, L

G. Kulkarni, L. Taneja, S. Aarav, A. K. Jha, Angular Schmidt spectrum of entangled pho- tons: Derivation of an exact formula and experimental characterization for noncollinear phase matching.Physical Review A97(6), 063846 (2018), doi:10.1103/physreva.97.063846

work page doi:10.1103/physreva.97.063846 2018
[54]

Karan,et al., Phase matching in𝛽-barium borate crystals for spontaneous parametric down- conversion.Journal of Optics22(8), 083501 (2020), doi:10.1088/2040-8986/ab89e4

S. Karan,et al., Phase matching in𝛽-barium borate crystals for spontaneous parametric down- conversion.Journal of Optics22(8), 083501 (2020), doi:10.1088/2040-8986/ab89e4

work page doi:10.1088/2040-8986/ab89e4 2020
[55]

G. P. Agrawal,Nonlinear Fiber Optics(Springer Berlin Heidelberg), pp. 195–211, doi:10. 1007/3-540-46629-0 9
[56]

Zhang, F

Y. Zhang, F. S. Roux, M. McLaren, A. Forbes, Radial modal dependence of the azimuthal spectrum after parametric down-conversion.Physical Review A89(4), 043820 (2014), doi: 10.1103/physreva.89.043820

work page doi:10.1103/physreva.89.043820 2014
[57]

Kulkarni, V

G. Kulkarni, V. Subrahmanyam, A. K. Jha, Intrinsic upper bound on two-qubit polarization entanglement predetermined by pump polarization correlations in parametric down-conversion. Physical Review A93(6), 063842 (2016), doi:10.1103/physreva.93.063842. 26

work page doi:10.1103/physreva.93.063842 2016
[58]

A. K. Jha,et al., Fourier relationship between the angle and angular momentum of entangled photons.Physical Review A78(4), 043810 (2008), doi:10.1103/physreva.78.043810

work page doi:10.1103/physreva.78.043810 2008
[59]

J. W. Goodman,Introduction to Fourier optics(Roberts and Company Publishers, Englewood) (2005)

2005
[60]

Karan, Ruchi, P

S. Karan, Ruchi, P. Mohta, A. K. Jha, Quantifying polarization changes induced by rotating Dove prisms and K-mirrors.Applied Optics61(28), 8302 (2022), doi:10.1364/ao.472543

work page doi:10.1364/ao.472543 2022
[61]

Karan, N

S. Karan, N. Senapati, A. K. Jha, Wavefront rotator with near-zero mean polarization change. Applied Optics63(17), 4552 (2024), doi:10.1364/ao.522420. Acknowledgments We acknowledge fruitful discussions with Prof. Martin P. van Exter from Leiden University, The Netherlands on this work. Funding:We acknowledge financial support from the Science and Enginee...

work page doi:10.1364/ao.522420 2024