Integrated quantum photonics
Integrated quantum photonics, uses photonic integrated circuits to control photonic quantum states for applications in quantum technologies.[1] As such, integrated quantum photonics provides a promising approach to the miniaturisation and scaling up of optical quantum circuits.[2] The major application of integrated quantum photonics is Quantum technology:, for example quantum computing,[3] quantum communication, quantum simulation,[4][5][6][7] quantum walks[8][9] and quantum metrology.
History
Linear optics was not seen as a potential technology platform for quantum computation until the seminal work of Knill, Laflamme, and Milburn,[10] which demonstrated the feasibility of linear optical quantum computers using detection and feed-forward to produce deterministic two-qubit gates. Following this there were several experimental proof-of-principle demonstrations of two-qubit gates performed in bulk optics.[11][12][13] It soon became clear that integrated optics could provide a powerful enabling technology for this emerging field.[14] Early experiments in integrated optics demonstrated the feasibility of the field via demonstrations of high-visibility non-classical and classical interference. Typically, linear optical components such as directional couplers (which act as beamsplitters between waveguide modes), and phase shifters to form nested Mach–Zehnder interferometers[15][16][17] are used to encode qubit in the spatial degree of freedom. That is, a single photon is in super position between two waveguides, where the zero and one state of the qubit correspond to the photon's presence in one or the other waveguide. These basic components are combined to produce more complex structures, such as entangling gates and reconfigurable quantum circuits.[18][19] Reconfigurability is achieved by tuning the phase shifters, which leverage thermo- or electro-optical effects.[20][21][22][23]
Another area of research in which integrated optics will prove pivotal in its development is Quantum communication and has been marked by extensive experimental development demonstrating, for example, quantum key distribution (QKD),[24][25] quantum relays based on entanglement swapping, and quantum repeaters.
Since the birth of integrated quantum optics experiments have ranged from technological demonstrations, for example integrated single photon sources[26][27][28] and integrated single photon detectors,[29] to fundamental tests of nature,[30][31] new methods for quantum key distribution,[32] and the generation of new quantum states of light.[33] It has also been demonstrated that a single reconfigurable integrated device is sufficient to implement the full field of linear optics, by using a reconfigurable universal interferometer.[18][34][35]
As the field has progressed new quantum algorithms have been developed which provide short and long term routes towards the demonstration of the superiority of quantum computers over their classical counterparts. Cluster state quantum computation is now generally accepted as the approach that will be used to develop a fully fledged quantum computer.[36] Whilst development of quantum computer will require the synthesis of many different aspects of integrated optics, boson sampling[37] seeks to demonstrate the power of quantum information processing via technologies readily available and is therefore a very promising near term algorithm to doing so. In fact shortly after its proposal there were several small scale experimental demonstrations of the boson sampling algorithm[38][39][40][41]
Introduction
Quantum photonics is the science of generating, manipulating and detecting light in regimes where it is possible to coherently control individual quanta of the light field (photons).[42] Historically, quantum photonics has been fundamental to exploring quantum phenomena, for example with the EPR paradox and Bell test experiments,.[43][44] Quantum photonics is also expected to play a central role in advancing future technologies, such as Quantum computing, Quantum key distribution and Quantum metrology. Photons are particularly attractive carriers of quantum information due to their low decoherence properties, light-speed transmission and ease of manipulation. Quantum photonics experiments traditionally involved 'bulk optics' technology—individual optical components (lenses, beamsplitters, etc.) mounted on a large optical table, with combined mass of hundreds of kilograms.
Integrated quantum photonics application of photonic integrated circuit technology to quantum photonics,[1] and seen as an important step in developing useful quantum technology. Photonic chips offer the following advantages over bulk optics:
- Miniaturisation - Size, weight and power consumption are reduced by orders of magnitude by virtue of smaller system size.
- Stability - Miniaturised components produced with advanced lithographic techniques produce waveguides and components which are inherently phase stable (coherent) and do not require optical alignment
- Experiment size - Large numbers of optical components can be integrated on a device measuring a few square centimetres.
- Manufacturability - Devices can be mass manufactured with very little increase in cost.
Being based on well-developed fabrication techniques, the elements employed in Integrated Quantum Photonics are more readily miniaturisable, and products based on this approach can be manufactured using existing production methodologies.
Materials
Control over photons can be achieved with integrated devices that can be realised in different material platforms such as silica, silicon, gallium arsenide, lithium niobate and indium phosphide and silicon nitride.
Silica
Two methods for using silica:
- Flame hydrolisis.
- Photolithography.
- Direct write - only uses single material and laser (use computer controlled laser to damage the glass and user lateral motion and focus to write paths with required refractive indices to produce waveguides). This method has the benefit of not needing a clean room. This is the most common method now for making silica waveguides, and is excellent for rapid prototyping. It has also been used in several demonstrations of topological photonics.[45]
The main challenges of the silica platform are the low refractive index contrast, the lack of active tunability post fabrication (as opposed to all the other platforms) and the difficulty of mass production with reproducibility and high yield due to the serial nature of the inscription process. Recent work has shown the possibility of dynamically reconfiguring these silica devices using heaters, albeit requiring moderately high power.[23]
Silicon
A big advantage of using silicon is that the circuits can be tuned actively using integrated thermal microheaters or p-i-n modulators, after the devices have been fabricated. The other big benefit of silicon is its compatibility with CMOS technology, which allows leveraging the mature fabrication infrastructure of the semiconductor electronics industry. The structures are different from modern electronic ones, however, they are readily scalable. Silicon has a really high refractive index of ~3.5 at the 1550 nm wavelength commonly used in optical telecommunications. It therefor offers one of the highest component densities in integrated photonics. The large contrast in refractive index with class (1.44) allows waveguides formed of silicon surrounded by glass to have very tight bends, which allows for high-density of components and reduced system size. Large silicon-on-insulator (SOI) wafers up to 300 mm in diameter can be obtained commercially, making the technology both available and reproducible. Many of the largest systems (up to several hundred components) have been demonstrated on the silicon photonics platform, with up to eight simultaneous photons, generation of graph states (cluster states), and up to 15 dimensional qudits).[46][47] Photon sources in silicon waveguide circuits leverage silicon's third-order nonlinearity to produce pairs of photons in spontaneous four-wave mixing. Silicon is opaque for wavelengths of light below ~1200 nm, limiting applicability to infra-red photons. Phase modulators based on thermo-optic and electro-optic phases are characteristically slow (KHz) and lossy (several dB) respectively, limiting applications and the ability to perform feed-forward measurements for quantum computation)
Lithium Niobate
Lithium niobate offers a large second-oder optical nonlinearity, enabling generation of photon pairs via spontaneous parametric down-conversion. This can also be leveraged to manipulate phase and perform mode conversion at fast speeds, and offer a promising route to feed-forward for quantum computation, multiplexed (deterministic) single photons sources). Historically waveguides are defined using titanium indiffusion, resulting in large waveguides (cm bend radius) but recent progress in processing has enabled thin film lithium niobate waveguides now offer competitive losses and density, surpassing that of silicon.
Fabrication
Conventional fabrication technologies are based on photolithographic processes, which enable strong miniaturization and mass production. In quantum optics applications a relevant role has been played also by the direct inscription of the circuits by femtosecond lasers[48] or UV lasers;[15] these are serial fabrication technologies, which are particularly convenient for research purposes, where novel designs have to be tested with rapid fabrication turnaround.
However, laser-written waveguides are not suitable for mass production and miniaturization due to the serial nature of the inscription technique, and due to the very low refractive index contrast allowed by these materials, as opposed to silicon photonic circuits. Femtosecond laser written quantum circuits have proven particularly suited for the manipulation of the polarization degree of freedom[49][50][51][52] and for building circuits with innovative three-dimensional design.[53][54][55][56] Quantum information is encoded on-chip in either the path, polarisation, time bin or frequency state of the photon, and manipulated using active integrated components in a compact and stable manner.
Components
Though the same fundamental components are used in quantum as classical photonic integrated circuits, there are also some practical differences. Since amplification of single photon quantum states is not possible (no-cloning theorem), loss is the top priority in components in quantum photonics.
Single photon sources are built from building blocks (waveguides, directional couplers, phase shifters). Typically, optical ring resonators, and long waveguide sections provide increased nonlinear interaction for photon pair generation, though progress is also being made to integrate solid state systems single photon sources based on quantum dots, and nitrogen-vacancy centers with waveguide photonic circuits.
References
- Politi A, Matthews JC, Thompson MG, O'Brien JL (2009). "Integrated Quantum Photonics". IEEE Journal of Selected Topics in Quantum Electronics. 15 (6): 1673–1684. Bibcode:2009IJSTQ..15.1673P. doi:10.1109/JSTQE.2009.2026060. S2CID 124841519.
- He YM, Clark G, Schaibley JR, He Y, Chen MC, Wei YJ, et al. (June 2015). "Single quantum emitters in monolayer semiconductors". Nature Nanotechnology. 10 (6): 497–502. arXiv:1003.3928. Bibcode:2009NaPho...3..687O. doi:10.1038/nphoton.2009.229. PMID 25938571. S2CID 20523147.
- Ladd TD, Jelezko F, Laflamme R, Nakamura Y, Monroe C, O'Brien JL (March 2010). "Quantum computers". Nature. 464 (7285): 45–53. arXiv:1009.2267. Bibcode:2010Natur.464...45L. doi:10.1038/nature08812. PMID 20203602. S2CID 4367912.
- Alán AG, Walther P (2012). "Photonic quantum simulators". Nature Physics (Submitted manuscript). 8 (4): 285–291. Bibcode:2012NatPh...8..285A. doi:10.1038/nphys2253.
- Georgescu IM, Ashhab S, Nori F (2014). "Quantum Simulation". Rev. Mod. Phys. 86 (1): 153–185. arXiv:1308.6253. Bibcode:2014RvMP...86..153G. doi:10.1103/RevModPhys.86.153. S2CID 16103692.
- Peruzzo A, McClean J, Shadbolt P, Yung MH, Zhou XQ, Love PJ, et al. (July 2014). "A variational eigenvalue solver on a photonic quantum processor". Nature Communications. 5: 4213. arXiv:1304.3061. Bibcode:2014NatCo...5.4213P. doi:10.1038/ncomms5213. PMC 4124861. PMID 25055053.
- Lodahl, Peter (2018). "Quantum-dot based photonic quantum networks". Quantum Science and Technology. 3 (1): 013001. arXiv:1707.02094. Bibcode:2018QS&T....3a3001L. doi:10.1088/2058-9565/aa91bb. S2CID 119359382.
- Peruzzo A, Lobino M, Matthews JC, Matsuda N, Politi A, Poulios K, et al. (September 2010). "Quantum walks of correlated photons". Science. 329 (5998): 1500–3. arXiv:1006.4764. Bibcode:2010Sci...329.1500P. doi:10.1126/science.1193515. PMID 20847264. S2CID 13896075.
- Crespi A, Osellame R, Ramponi R, Giovannetti V, Fazio R, Sansoni L, et al. (2013). "Anderson localization of entangled photons in an integrated quantum walk". Nature Photonics. 7 (4): 322–328. arXiv:1304.1012. Bibcode:2013NaPho...7..322C. doi:10.1038/nphoton.2013.26. S2CID 119264896.
- Knill E, Laflamme R, Milburn GJ (January 2001). "A scheme for efficient quantum computation with linear optics". Nature. 409 (6816): 46–52. Bibcode:2001Natur.409...46K. doi:10.1038/35051009. PMID 11343107. S2CID 4362012.
- O'Brien JL, Pryde GJ, White AG, Ralph TC, Branning D (November 2003). "Demonstration of an all-optical quantum controlled-NOT gate". Nature. 426 (6964): 264–7. arXiv:quant-ph/0403062. Bibcode:2003Natur.426..264O. doi:10.1038/nature02054. PMID 14628045. S2CID 9883628.
- Pittman TB, Fitch MJ, Jacobs BC, Franson JD (2003-09-26). "Experimental controlled-NOT logic gate for single photons in the coincidence basis". Physical Review A. 68 (3): 032316. arXiv:quant-ph/0303095. Bibcode:2003PhRvA..68c2316P. doi:10.1103/PhysRevA.68.032316. S2CID 119476903.
- Okamoto R, O'Brien JL, Hofmann HF, Takeuchi S (June 2011). "Realization of a Knill-Laflamme-Milburn controlled-NOT photonic quantum circuit combining effective optical nonlinearities". Proceedings of the National Academy of Sciences of the United States of America. 108 (25): 10067–71. arXiv:1006.4743. Bibcode:2011PNAS..10810067O. doi:10.1073/pnas.1018839108. PMC 3121828. PMID 21646543.
- Tanzilli S, Martin A, Kaiser F, De Micheli MP, Alibart O, Ostrowsky DB (2012-01-02). "On the genesis and evolution of Integrated Quantum Optics". Laser & Photonics Reviews. 6 (1): 115–143. arXiv:1108.3162. Bibcode:2012LPRv....6..115T. doi:10.1002/lpor.201100010. ISSN 1863-8899. S2CID 32992530.
- Smith BJ, Kundys D, Thomas-Peter N, Smith PG, Walmsley IA (August 2009). "Phase-controlled integrated photonic quantum circuits". Optics Express. 17 (16): 13516–25. arXiv:0905.2933. Bibcode:2009OExpr..1713516S. doi:10.1364/OE.17.013516. PMID 19654759. S2CID 8844497.
- Politi A, Cryan MJ, Rarity JG, Yu S, O'Brien JL (May 2008). "Silica-on-silicon waveguide quantum circuits". Science. 320 (5876): 646–9. arXiv:0802.0136. Bibcode:2008Sci...320..646P. doi:10.1126/science.1155441. PMID 18369104. S2CID 3234732.
- Laing A, Peruzzo A, Politi A, Verde MR, Halder M, Ralph TC, et al. (2010). "High-fidelity operation of quantum photonic circuits". Applied Physics Letters. 97 (21): 211109. arXiv:1004.0326. Bibcode:2010ApPhL..97u1109L. doi:10.1063/1.3497087. S2CID 119169684.
- Carolan J, Harrold C, Sparrow C, Martín-López E, Russell NJ, Silverstone JW, et al. (August 2015). "QUANTUM OPTICS. Universal linear optics". Science. 349 (6249): 711–6. arXiv:1505.01182. doi:10.1126/science.aab3642. PMID 26160375. S2CID 19067232.
- Bartlett, Ben; Fan, Shanhui (2020-04-20). "Universal programmable photonic architecture for quantum information processing". Physical Review A. 101 (4): 042319. arXiv:1910.10141. doi:10.1103/PhysRevA.101.042319.
- Miya RT (2000). "Silica-based planar lightwave circuits: passive and thermally active devices". IEEE Journal of Selected Topics in Quantum Electronics. 6 (1): 38–45. Bibcode:2000IJSTQ...6...38M. doi:10.1109/2944.826871. S2CID 6721118.
- Wang J, Santamato A, Jiang P, Bonneau D, Engin E, Silverstone JW, et al. (2014). "Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits". Optics Communications. 327: 49–55. arXiv:1403.2635. Bibcode:2014OptCo.327...49W. doi:10.1016/j.optcom.2014.02.040. S2CID 21725350.
- Chaboyer Z, Meany T, Helt LG, Withford MJ, Steel MJ (April 2015). "Tunable quantum interference in a 3D integrated circuit". Scientific Reports. 5: 9601. arXiv:1409.4908. Bibcode:2015NatSR...5E9601C. doi:10.1038/srep09601. PMC 5386201. PMID 25915830.
- Flamini F, Magrini L, Rab AS, Spagnolo N, D'ambrosio V, Mataloni P, et al. (2015). "Thermally reconfigurable quantum photonic circuits at telecom wavelength by femtosecond laser micromachining". Light: Science & Applications. 4 (11): e354. arXiv:1512.04330. Bibcode:2015LSA.....4E.354F. doi:10.1038/lsa.2015.127. S2CID 118584043.
- Zhang P, Aungskunsiri K, Martín-López E, Wabnig J, Lobino M, Nock RW, et al. (April 2014). "Reference-frame-independent quantum-key-distribution server with a telecom tether for an on-chip client". Physical Review Letters. 112 (13): 130501. arXiv:1308.3436. Bibcode:2014PhRvL.112m0501Z. doi:10.1103/PhysRevLett.112.130501. PMID 24745397. S2CID 8180854.
- Metcalf BJ, Spring JB, Humphreys PC, Thomas-Peter N, Barbieri M, Kolthammer WS, et al. (2014). "Quantum teleportation on a photonic chip". Nature Photonics. 8 (10): 770–774. arXiv:1409.4267. Bibcode:2014NaPho...8..770M. doi:10.1038/nphoton.2014.217. S2CID 109597373.
- Silverstone JW, Bonneau D, Ohira K, Suzuki N, Yoshida H, Iizuka N, et al. (2014). "On-chip quantum interference between silicon photon-pair sources". Nature Photonics. 8 (2): 104–108. arXiv:1304.1490. doi:10.1038/nphoton.2013.339. S2CID 21739609.
- Spring JB, Salter PS, Metcalf BJ, Humphreys PC, Moore M, Thomas-Peter N, et al. (June 2013). "On-chip low loss heralded source of pure single photons". Optics Express. 21 (11): 13522–32. arXiv:1304.7781. doi:10.1364/oe.21.013522. PMID 23736605. S2CID 1356726.
- Dousse A, Suffczyński J, Beveratos A, Krebs O, Lemaître A, Sagnes I, et al. (July 2010). "Ultrabright source of entangled photon pairs". Nature. 466 (7303): 217–20. Bibcode:2010Natur.466..217D. doi:10.1038/nature09148. PMID 20613838. S2CID 3053956.
- Sahin D, Gaggero A, Weber JW, Agafonov I, Verheijen MA, Mattioli F, et al. (2015). "Waveguide Nanowire Superconducting Single-Photon Detectors Fabricated on GaAs and the Study of Their Optical Properties". IEEE Journal of Selected Topics in Quantum Electronics. 21 (2): 2359539. Bibcode:2015IJSTQ..2159539S. doi:10.1109/JSTQE.2014.2359539. S2CID 37594060.
- Shadbolt P, Mathews JC, Laing A, O'brien JL (2014). "Testing foundations of quantum mechanics with photons". Nat Phys. 10 (4): 278–286. arXiv:1501.03713. Bibcode:2014NatPh..10..278S. doi:10.1038/nphys2931. S2CID 118523657.
- Peruzzo A, Shadbolt P, Brunner N, Popescu S, O'Brien JL (November 2012). "A quantum delayed-choice experiment". Science. 338 (6107): 634–7. arXiv:1205.4926. Bibcode:2012Sci...338..634P. doi:10.1126/science.1226719. PMID 23118183. S2CID 3725159.
- Sibson P, Erven C, Godfrey M, Miki S, Yamashita T, Fujiwara M, et al. (February 2017). "Chip-based quantum key distribution". Nature Communications. 8: 13984. arXiv:1509.00768. doi:10.1038/ncomms13984. PMC 5309763. PMID 28181489.
- Orieux A, Ciampini MA, Mataloni P, Bruß D, Rossi M, Macchiavello C (October 2015). "Experimental Generation of Robust Entanglement from Classical Correlations via Local Dissipation". Physical Review Letters. 115 (16): 160503. arXiv:1503.05084. Bibcode:2015PhRvL.115p0503O. doi:10.1103/PhysRevLett.115.160503. PMID 26550856. S2CID 206263195.
- Harris NC, Steinbrecher GR, Mower J, Lahini Y, Prabhu M, Baehr-Jones T, et al. (2015). "Bosonic transport simulations in a large-scale programmable nanophotonic processor". Nature Photonics. 11 (7): 447–452. arXiv:1507.03406. doi:10.1038/nphoton.2017.95. S2CID 4943152.
- Reck M, Zeilinger A, Bernstein HJ, Bertani P (July 1994). "Experimental realization of any discrete unitary operator". Physical Review Letters. 73 (1): 58–61. Bibcode:1994PhRvL..73...58R. doi:10.1103/PhysRevLett.73.58. PMID 10056719.
- Briegel HJ, Raussendorf R (January 2001). "Persistent entanglement in arrays of interacting particles". Physical Review Letters. 86 (5): 910–3. arXiv:quant-ph/0004051. Bibcode:2001PhRvL..86..910B. doi:10.1103/PhysRevLett.86.910. PMID 11177971. S2CID 21762622.
- Aaronson S, Arkhipov A. "The Computational Complexity of Linear Optics" (PDF). scottaaronson.
- Broome MA, Fedrizzi A, Rahimi-Keshari S, Dove J, Aaronson S, Ralph TC, White AG (February 2013). "Photonic boson sampling in a tunable circuit". Science. 339 (6121): 794–8. arXiv:1212.2234. Bibcode:2013Sci...339..794B. doi:10.1126/science.1231440. hdl:1721.1/85873. PMID 23258411. S2CID 22912771.
- Spring JB, Metcalf BJ, Humphreys PC, Kolthammer WS, Jin XM, Barbieri M, et al. (February 2013). "Boson sampling on a photonic chip". Science. 339 (6121): 798–801. arXiv:1212.2622. Bibcode:2013Sci...339..798S. doi:10.1126/science.1231692. PMID 23258407. S2CID 11687876.
- Tillmann M, Dakić B, Heilmann R, Nolte S, Szameit A, Walther P (2013). "Experimental boson sampling". Nat Photonics. 7 (7): 540–544. arXiv:1212.2240. Bibcode:2013NaPho...7..540T. doi:10.1038/nphoton.2013.102. S2CID 119241050.
- Crespi A, Osellame R, Ramponi R, Brod DJ, Galvao EF, Spagnolo N, Viteli C, Maiorino E, Mataloni P, Sciarrion F (2013). "Integrated multimode interferometers with arbitrary designs for photonic boson sampling". Nature Photonics. 7 (7): 545–549. arXiv:1212.2783. Bibcode:2013NaPho...7..545C. doi:10.1038/nphoton.2013.112.
- Pearsall, Thomas (2017). Quantum Photonics. Graduate Texts in Physics. Springer. doi:10.1007/978-3-319-55144-9. ISBN 9783319551425.
- Grangier P, Roger G, Aspect A (1981). "Experimental Tests of Realistic Local Theories via Bell's Theorem". Phys. Rev. Lett. 47 (7): 460–463. Bibcode:1981PhRvL..47..460A. doi:10.1103/PhysRevLett.47.460.
- Freedman SJ, Clauser JF (1972). "Experimental Test of Local Hidden-Variable Theories" (PDF). Phys. Rev. Lett. 28 (14): 938–941. Bibcode:1972PhRvL..28..938F. doi:10.1103/PhysRevLett.28.938.
- Ozawa T, Price HM, Amo A, Goldman N, Hafezi M, Lu L, et al. (2019). "Topological Photonics". Reviews of Modern Physics. 91 (1): 015006. arXiv:1802.04173. Bibcode:2019RvMP...91a5006O. doi:10.1103/RevModPhys.91.015006. S2CID 10969735.
- Adcock JC, Vigliar C, Santagati R, Silverstone JW, Thompson MG (August 2019). "Programmable four-photon graph states on a silicon chip". Nature Communications. 10 (1): 3528. arXiv:1811.03023. Bibcode:2019NatCo..10.3528A. doi:10.1038/s41467-019-11489-y. PMC 6684799. PMID 31388017.
- Schuck C, Pernice WH, Minaeva O, Li M, Gol'Tsman G, Sergienko AV, et al. (September 2019). "Generation and sampling of quantum states of light in a silicon chip". Nature Physics. 15 (9): 925–929. arXiv:1812.03158. Bibcode:2019NatPh..15..925P. doi:10.1038/s41567-019-0567-8. ISSN 1745-2473. S2CID 116319724.
- Marshall GD, Politi A, Matthews JC, Dekker P, Ams M, Withford MJ, O'Brien JL (July 2009). "Laser written waveguide photonic quantum circuits". Optics Express. 17 (15): 12546–54. arXiv:0902.4357. Bibcode:2009OExpr..1712546M. doi:10.1364/OE.17.012546. PMID 19654657. S2CID 30383607.
- Sansoni L, Sciarrino F, Vallone G, Mataloni P, Crespi A, Ramponi R, Osellame R (November 2010). "Polarization entangled state measurement on a chip". Physical Review Letters. 105 (20): 200503. arXiv:1009.2426. Bibcode:2010PhRvL.105t0503S. doi:10.1103/PhysRevLett.105.200503. PMID 21231214. S2CID 31712236.
- Crespi A, Ramponi R, Osellame R, Sansoni L, Bongioanni I, Sciarrino F, et al. (November 2011). "Integrated photonic quantum gates for polarization qubits". Nature Communications. 2: 566. arXiv:1105.1454. Bibcode:2011NatCo...2..566C. doi:10.1038/ncomms1570. PMC 3482629. PMID 22127062.
- Corrielli G, Crespi A, Geremia R, Ramponi R, Sansoni L, Santinelli A, et al. (June 2014). "Rotated waveplates in integrated waveguide optics". Nature Communications. 5: 4249. Bibcode:2014NatCo...5.4249C. doi:10.1038/ncomms5249. PMC 4083439. PMID 24963757.
- Heilmann R, Gräfe M, Nolte S, Szameit A (February 2014). "Arbitrary photonic wave plate operations on chip: realizing Hadamard, Pauli-X, and rotation gates for polarisation qubits". Scientific Reports. 4: 4118. Bibcode:2014NatSR...4E4118H. doi:10.1038/srep04118. PMC 3927208. PMID 24534893.
- Crespi A, Sansoni L, Della Valle G, Ciamei A, Ramponi R, Sciarrino F, et al. (March 2015). "Particle statistics affects quantum decay and Fano interference". Physical Review Letters. 114 (9): 090201. arXiv:1409.8081. Bibcode:2015PhRvL.114i0201C. doi:10.1103/PhysRevLett.114.090201. PMID 25793783. S2CID 118387033.
- Gräfe M, Heilmann R, Perez-Leija A, Keil R, Dreisow F, Heinrich M, et al. (31 August 2014). "On-chip generation of high-order single-photon W-states". Nature Photonics. 8 (10): 791–795. Bibcode:2014NaPho...8..791G. doi:10.1038/nphoton.2014.204. S2CID 85442914.
- Spagnolo N, Vitelli C, Aparo L, Mataloni P, Sciarrino F, Crespi A, et al. (2013). "Three-photon bosonic coalescence in an integrated tritter". Nature Communications. 4: 1606. arXiv:1210.6935. Bibcode:2013NatCo...4.1606S. doi:10.1038/ncomms2616. PMID 23511471. S2CID 17331551.
- Crespi A, Osellame R, Ramponi R, Bentivegna M, Flamini F, Spagnolo N, et al. (February 2016). "Suppression law of quantum states in a 3D photonic fast Fourier transform chip". Nature Communications. 7: 10469. Bibcode:2016NatCo...710469C. doi:10.1038/ncomms10469. PMC 4742850. PMID 26843135.