Nonlinear photonic quantum gates

Schematic of a graphene-based two-photon gate

Sub-threshold OPO generating narrow-band photons

Laser spectroscopy for frequency stabilization

For improving the scalability of entirely linear-optical quantum computing schemes we are doing research on strong nonlinear media that enable effective photon-photon interactions. One approach is based on the preparation of narrow-bandwidth single photons that are resonant to transitions of cold atoms that introduce strong nonlinear interactions. Alternatively we are also investigating graphene as strong nonlinear medium. Recently it has been shown that nanostructured graphene has a remarkably strong nonlinear response, which can be made substantial even at the single-photon level. Our group is testing graphene’s nonlinear properties and its use for deterministic two-photon logic gates that can operate at room temperature and without vacuum conditions.


Publications (selected):

Giant enhancement of third-harmonic generation in graphene–metal heterostructures
I. Alonso Calafell, L.A. Rozema, D. Alcaraz Iranzo, A. Trenti, P.K. Jenke, J.D. Cox, A. Kumar, H. Bieliaiev, S. Nanot, C. Peng, D.K. Efetov, J.Y. Hong, J. Kong, D.R. Englund, F. J. García de Abajo, F. H. L. Koppens, P. Walther,
Nature Nanotechnology 16, 318–324 (2021).

Novel single-mode narrow-band photon source of high brightness tuned to cesium D2 line
A. Moqanaki, F. Massa, P. Walther,
APL Photonics 4, 090804 (2019).

Quantum computing with graphene plasmons
I. Alonso Calafell, J. D. Cox, M. Radonjić, J. R. M. Saavedra, F. J. García de Abajo,
L. A. Rozema, P. Walther
npj Quantum Information 5, 37 (2019).



Electrically tunable nonlinear plasmonics in graphene nanoislands
J.D. Cox, F.J.G. de Abajo
Nature Communications 5, 5725 (2014).

Single-Photon Nonlinear Optics with Graphene Plasmons
M. Gullans, D.E. Chang, F.H.L. Koppens, F.J.G. de Abajo, M.D. Lukin
Physical Review Letters 111, 247401 (2013).

Coherent Nonlinear Optical Response of Graphene
E. Hendry, P.J. Hale, J. Moger, A.K. Savchenko, S.A. Mikhailov
Physical  Review Letters 105, 097401 (2010).


Further publications...