Quantum Photonics

The Quantum Photonics Group investigates the quantum interaction between light and matter in a solid-state platform.

Our quest is to develop a deterministic photon-emitter interface based using quantum emitters and photonic nanostructures for real-world quantum technology applications within quantum communication towards the Quantum Internet.

Quantum Photonics at the Niels Bohr Institute Quantum Photonics at the Niels Bohr Institute Quantum Photonics at the Niels Bohr Institute Quantum Photonics at the Niels Bohr Institute Quantum Photonics at the Niels Bohr Institute

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Deterministic generation of entangled photons

Device-independent cryptography achieves unbreakable security by exploiting quantum correlations (e.g. entanglement) between the sender and the receiver. The practical implementation of such protocols requires efficient and high-fidelity entangled photon sources. Solid state emitters are the way forward for efficient quantum light generation due to the possibility to integrate them into a nanophotonic structure. Recent demonstrations of high-fidelity (> 97%) polarization entanglement using the biexciton cascade in GaAs/AlGaAs quantum dots open exciting route for deterministic entanglement generation. The project will deal with several aspects of the nanophotonic interfacing of these quantum dots including: 1) Efficient preparation of the quantum dot, 2) Extraction of entangled photon pairs and state tomography, 3) Sources of noise limiting the entanglement fidelity, 4) near-future applications of the entangled photons for cryptography. For more information, contact Prof. Peter Lodahl (lodahl@nbi.ku.dk).

Coherent single photons: Interfacing with memories

The distribution of quantum states across nodes in a quantum network is the key requirement for secure communication and distributed computing. A typical quantum network will involve interfacing disparate qubits (matter, photon, spin, etc.) to ensure maximum efficiency. Photons are robust carriers of information and hence are critical for interconnection. The disparity between the frequency and bandwidth across the qubits pose challenges in the interconnection. Efficiently crafting the bandwidth of the photon is the key enabler for photonic interconnects. Quantum dot single photon sources typically generate photons with GHz bandwidth. Efficient interfacing of photons with quantum memories (holding time ~ 0.1 – 1 us) requires ~10 MHz bandwidth. A promising way forward to achieve such coherent single photons is through Raman processes in a Λ system. The project will deal with coherent photon generation using one of the Λ-systems of a trion in a InAs quantum dot.  Key aspects: 1) Branching ratio and limits on the bandwidth of photons, 2) Generation and characterization  3) Pulse shaping for bandwidth manipulation. For more information, contact Prof. Peter Lodahl (lodahl@nbi.ku.dk).

Nonlinear chiral quantum optics

Chiral quantum light-matter interactions are a recently discovered consequence of using nanophotonic platforms for quantum optical experiments.  In chiral scenarios, the light-matter interaction is strongly directional, meaning that the interaction of photons with a quantum dot strongly depends on which way they travel, allowing for the design of novel and non-reciprocal quantum devices. Within this project, we will explore the nonlinearity of such chiral quantum interactions, using a blend of numerical modelling and optical experiments. For more information, contact Prof. Peter Lodahl (lodahl@nbi.ku.dk).

Giant cooperativity in planar structures

Cooperativity is a fundamental property within quantum optics that captures the strength of the coupling between light (photons) and matter (quantum emitters).  Within this project, we wish to enhance this cooperativity using resonant, planar nanophotonic structures, thereby setting the stage for the creation of efficient and complex quantum architecture. For more information, contact Prof. Peter Lodahl (lodahl@nbi.ku.dk).

Multicolour quantum optics

Quantum emitters such as quantum dots are inherently nonlinear at the ultimate, low-energy limit; after all, they can only absorb a single photon at a time.  This inherently large nonlinearity means that the interaction of a single emitter with a single photon can be significantly tuned by a single, control photon.  Within this project, we will model this multicolour nonlinear interaction and search for signatures of our model in optical experiments. For more information, contact Prof. Peter Lodahl (lodahl@nbi.ku.dk).

Topological quantum photonics

Topological photonic edge states, which exist at the interface between especially engineered photonic crystals, have recently been shown to guide photons emitted by a single quantum dot.  This has generated considerable excitement within the quantum photonics community as these edge modes are protected from backscattering due to defects or fabrication imperfections and, additionally, allow for directional and non-reciprocal light-matter interactions.  Within this project, we will study quantum light-matter interactions with topological edge-states using numerical modelling techniques. For more information, contact Prof. Peter Lodahl (lodahl@nbi.ku.dk).

Scalable chip-to-fiber coupling

The project aims at building an off-chip fiber delay based on optical fibers. Off-chip fiber delays are key ingredients for performing advanced quantum protocols and emitter de-multiplexing. Based on our state-of-the-art chip-to-fiber couplers, we are planning to couple multiple fibers to nanophotonic waveguides using matrix arrays. The project involves building/adapting a room-temperature setup for aligning and bonding chips to matrix arrays, perform numerical simulations of the optimal power transfer to fibers, design and (optionally) fabricate the chip and measure it in the lab. For more information, contact Asst. Prof. Leonardo Midolo (midolo@nbi.ku.dk).

Resonance fluorescence and Purcell enhancement

The goal is to design a device that enables a scheme for resonantly driving an emitter inside a cavity. There are different strategies that involve combining a tunable cavity and a waveguide-based resonant excitation scheme. The project involves numerical simulations of the device to improve the extinction between the pump laser and the emitted photons. The device is then characterized in the lab. Optionally, the student has the possibility to get training to the cleanroom and fabricate the sample. For more information, contact Asst. Prof. Leonardo Midolo (midolo@nbi.ku.dk).

Electro-optical routing of single-photons

Design a waveguide-based electro-optic switch operating at >10 MHz for fast optical routing of photons. The router is key to implement protocols for de-multiplexing single-photons. Based on our recent results in electro-optic routing technology, we plan to build an integrated Mach-Zehnder interferometer with embedded phase shifters. The project involves the design, fabrication, and characterization of the device. An interest in acquiring nanofabrication skills is preferred.  For more information, contact Asst. Prof. Leonardo Midolo (midolo@nbi.ku.dk).

 

Chippen over dem alle
The chip over them all

Peter Lodahl interviewed: De skal løse de store problemer: Kvantecomputere trodser enhver logik
Peter Lodahl interviewed: They should solve all the big problems: The quantum computer defies all logic

Kvantestartup er klar med sin første revolutionerende chip
Quantum startup is ready with their first revolutionary chip. 

Danske forskere krypterede samtale med kvanteteknologi og en hacker gik i fælden
Danish researchers encrypted conversation with quantum technology and a hacker got caught
Articles on the quantum encrypted channel between DTU and NBI.

Nyt firma vil masseproducere qubit til optisk kvantecomputer
New company will mass produce qubits for optical quantum computers

Kvantecomputeren - det nye rumkapløb
The quantum computer - the new space race

Dansk chip kan danne grundlag for optiske kvantesimulatorer
Danish chip will form the foundation for optical quantum simulators

Kvante-gennembrud: Dansk opfindelse kan give computere superkræfter
Quantum breakthrough: Danish invention can give computers superpowers

Megabevilling til kvantesimulatorer viser, at grundforskning lønner sig.
Large grant for quantumsimulators shows that fundamental research pays off.
Article (in Danish) on our new center Solid-state quantum simulators for biochemistry.

"Den interne proces var ekstrem. Vild og blodig."
"The internal process was extreme. Wild and bloody."
Profile (in Danish) of recent recognitions and scientific accomplishments by Prof. Peter Lodahl and his Quantum Photonics research group.

Danske forskere baner vejen for fremtidens computer.
Danish researchers pave the way for future computer.
Article (in Danish) on our recent effors towards implementing quantum technology.

Building the Quantum Internet.
Interesting article on how a solid-state material based quantum internet could be realized:

Chiral quantum optics, Nature (2017).
Highlighted in more than 25 news stories in scientific and general online magazine. Here are some examples:

Deterministic photon-emitter coupling in chiral photonic circuits, Nature Nanotechnology (2015).

Nonuniversal intensity correlations in a two-dimensional Anderson-localizing random medium, Physical Review Letters 109, 253902 (2012).

Optical cavity cooling of mechanical modes of a semiconductor nanomembrane, Nature Physics 8, 168-172 (2012).

Strongly Modified Plasmon-Matter Interaction with Mesoscopic Quantum Emitters, Nature Physics 7, 215-218 (2011).

Quantum Interference and Entanglement Induced by Multiple Scattering of Light, Phys. Rev. Lett. 105, 090501 (2010).

Cavity quantum electrodynamics with Anderson-localized modes, Science 327, 1352 (2010).

Observation of Spatial Quantum Correlations Induced by Multiple Scattering of Nonclassical Light, Phys. Rev. Lett. 102, 193901 (2009).

Podcast

  • Christiansen & Andersen, Lyset

Popular papers

1) P. Lodahl, At kontrollere udsendelsen af lys (in Danish), Aktuel Naturvidenskab 4, 15-17 (2004).

2) P. Lodahl and W. L. Vos, Controlling spontaneous emission with photonic crystals, Photonics Spectra 39 (3): 64+ MAR (2005).

3) P. Lodahl, Lys i fotoniske krystaller og optiske nanobokse (in Danish), Naturens Verden 1, p. 29-35 (2006).

4) P.T. Kristensen, P. Lodahl, and J. Mørk, To decay or not to decay – or both! Quantum mechanics of spontaneous emission, DOPS Nyt 1, p. 4-8 (2008).

 

The Quantum, Photonics group is part of the Quantum Optics section at NBI and collaborates to a large extend with the other theoretical and experimental groups in the section. 

Peter Lodahl
Professor
Blegdamsvej 17, Bld. T
Phone: +45 35 32 53 06
E-mail: lodahl@nbi.ku.dk
CV and Short bio
List of publications

Leonardo Midolo
Associate p
rofessor
Blegdamsvej 17, Bld. T
Phone: +45 23 23 41 69
E-mail: midolo@nbi.ku.dk
Personal page


Atefeh Shadmani 
Postdoc
Blegdamsvej 17
Phone: +45 35 33 44 39
E-mail: shadmani@nbi.ku.dk

Marcus Albrechtsen
Postdoc
Blegdamsvej 17
Phone: 
E-mail: 

Ming Lai Chan
Postdoc
Blegdamsvej 17, Bld. H
Phone: +45 71 45 61 67
E-mail: Ming-Lai.Chan@nbi.ku.dk
Personal page

Patrik Isene Sund
PhD fellow
Blegdamsvej 17, Bld. F
Phone: +45 35 32 12 90
E-mail: patrik.sund@nbi.ku.dk
Personal page

Rodrigo Thomas
Postdoc
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Shikai Liu
Postdoc
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Sjaak Cornelis van Diepen
Postdoc
Blegdamsvej 17
Phone: +45 35 32 38 16
E-mail: cornelis.diepen@nbi.ku.dk
Personal page

Stefano Paesani
Postdoc
Blegdamsvej 17
Phone: +45 35 33 63 86
E-mail: stefano.paesani@nbi.ku.dk
Personal page

Yijian Meng
Postdoc
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Ying Wang
Postdoc
Blegdamsvej 17, Bld. F
Phone: +45 35 33 14 04
E-mail: ying.wang@nbi.ku.dk
Personal page

Yu Meng
Postdoc
Blegdamsvej 17
Phone: +45 35 32 96 72
E-mail: yu.meng@nbi.ku.dk
Personal page

Carlos Fernando Duarte Faurby
PhD fellow
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Celeste Qvotrup
PhD fellow
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Hanna Salamon
PhD fellow
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Kasper Hede Nielsen
PhD fellow
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Mikkel Thorbjørn Mikkelsen
PhD fellow
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Martin Saurbrey Bjergfelt
Academic lab technician
Juliane Maries Vej 30
Phone: +45 35 33 08 46
E-mail: martin.bjergfelt@nbi.ku.dk
Personal page

Mikkel Torrild Hansen
Scientific assistant
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Nikolaos Andrianopoulous
Scientific assistant
Blegdamsvej 17
Phone:
E-mail: 
Personal page

Zhe Liu
Academic lab technician, Engineer 
Universitetsparken 5, HCØ
Phone: +45 35 33 05 20
E-mail: zhe.liu@nbi.ku.dk
Personal page


Master students
Mai Skaar Kristensen
Thomas Sandø-Pedersen
Christian Hjort Christiansen
Arnulf Johannes Snedker-Nielsen


Frederik Uldall
Senior adviser
Blegdamsvej 17, Bld. T
Phone: +45 35 32 24 14
E-mail: frederik.uldall@nbi.ku.dk
Personal page

Charlotte Hviid
Administrative coordinator
Blegdamsvej 17, Bld. T
Phone: +45 35 32 52 54
E-mail: hviid@nbi.ku.dk
Personal page

Dorte Christiane Garde Nielsen
Research secretary
Blegdamsvej 17, Bld. T
Phone: +45 35 33 01 80
E-mail: dorte.garde.nielsen@nbi.ku.dk
Personal page

Anna Ingmer Boye
Student assistant
Blegdamsvej 17, Bld. T
E-mail: anna.boye@nbi.ku.dk


Alumni

Alexey Tiranov
Postdoc

Asli Dilara Ugurlu
PhD fellow

Beatrice da Lio
Postdoc

Camille Papon
PhD fellow

Freja Thilde Østfeldt
Postdoc

Hanna Le Jeannic
Postdoc

Jacques Johannes Carolan
Postdoc

Laurits Moestrup Høgel
Research Assistant

Martin Hayhurst Appel
PhD fellow

Nils Valentin Hauff
PhD fellow 

Nir Rotenberg
Assistant professor

Pratyush Anand
Research Assistant

Ravitej Uppu
Assistant professor

Vasiliki Angelopoulou
PhD fellow

Xiao-Liu Chu
Postdoc

Xiaoyan Zhou
Assistant professor

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Openings:

1) Senior postdoc and/or assistant/associate professor positions within a broad area of competences:
a) Photonic quantum simulation and quantum computing.
b) Photonic quantum networks and quantum communication with single photons.
 Read more about the positions here.

Peter Lodahl

Group leader

Peter Lodahl, Professor
Phone: 35 32 53 06
Email: lodahl@nbi.ku.dk
Google Scholar: Link