Mgr. Karel Lemr, Ph.D. ml.

Research interest

Logical gates for quantum computing

Kvantové hradlo Quantum mechanics provides revolutionary concepts such as the principle of superposition of quantum entanglement. It has been demonstrated that these phenomena can be used to increase efficiency of computing algorithms. The goal of quantum computing is to find their practical applications and ultimately construct the so-called quantum computer. Research in this area involves theoretical and experimental investigation of basic quantum gates (building elements for future quantum computers).

Quantum communications and cryptography

Quantum communications Quantum communications are a straightforward extension to quantum computing. This scientific field studies transmission of quantum information and related security concerns (cryptography). An interesting property of quantum information is the impossibility of its duplication. Quantum cryptography can make use of this property to prevent successful eavesdropping.

Quantum state engineering

Kvantové stavy Input quantum states are an indispensable ingredient to many quantum-information protocols. One of our experimental activities involves generation of useful quantum states such as Knill-Laflamme-Milburn states. Using linear-optical experimental setups and sources of entangled photon pairs we are able to produce more complex quantum states of light.

Time-resolved spectroscopy

Streak kamera Slightly different from previous fields of interests is the area of time-resolved spectroscopy. We use a streak camera with picosecond resolution to observe temporal properties of luminescence from nano-particles or organic molecules.

Brief curriculum vitae

Personal details

  • born on 9th August 1984 In Kadan, Czech Republic
  • married, 1 son


  • 1997 – 2003
lyceum Slovanské gymnázium Olomouc,
Czech-French section
  • 2003 – 2006
bachelor’s degree, Palacky University in Olomouc,
Optics and Optoelectronics
  • 2006 – 2008
master’s degree, Palacky University in Olomouc,
Optics and Optoelectronics
  • 2008 – 2012
Ph.D. degree, Palacky University in Olomouc,
Optics and Optoelectronics

Professional career

  • 2004 – 2010
lyceum teacher, Slovanské gymnázium Olomouc,
teaching physics in French
  • 2008 – 2014
Institute of Physics of the Czech Academy of Sciences
  • 2009 – 2012
Palacky University in Olomouc
  • 2012 – nyní
academic staff,
Palacky University in Olomouc


  • 2012
Werner von Siemens Excellence Award 2012 for best Ph.D. thesis
  • 2013
RCPTM annual award

Research visits and summer schools

  • 2008
quantum optics summer school, Hven, Sweden
  • 2010
research visit, Notre Dame University, Indiana, USA
  • 2013 – present
series of short-term research visits,
Adam Mickiewicz University, Poznan, Poland

Notable publications

Experimental Implementation of Optimal Linear-Optical Controlled-Unitary Gates

[K. Lemr, K. Bartkiewicz, A. Černoch, M. Dušek, J. Soubusta, Phys. Rev. Lett. 114, 153602 (2015)]

Lemr_PRL Efficient construction of various quantum gates is a crucial prerequisite for practical quantum computing and communications. We have experimentally demonstrated how to implement an optimal controlled-unitary gate using linear optics. This gate is particularly interesting since it is known to be a key component for quantum circuits design. Instead of using two CNOT gates, we use only one tunable controlled-phase gate. This way we can increase the success probability of the entire scheme by about an order of magnitude.

Eavesdropping on quantum cryptography using quantum cloning

[K. Bartkiewicz, K. Lemr, A. Černoch, J. Soubusta, A. Miranowicz, Phys. Rev. Lett. 110, 173601 (2013)]

Hradlo pro kontrolovanou změnu fáze Quantum cryptography is a method for secure transmission of information. There are however methods for eavesdropping on quantum cryptography exploiting various weaknesses. One of these methods is based on quantum cloning. We have experimentally implemented this method in our laboratory. Results of our research were reported on in Physical Review Letters and also in a number of journal articles.

Tunable linear-optical controlled-phase gate

[K. Lemr, A. Černoch, J. Subusta, K. Kieling, J. Eisert, M. Dušek, Phys. Rev. Lett. 106, 013602 (2011)]

Hradlo pro kontrolovanou změnu fáze In 2011, we have constructed in our laboratory a linear-optical quantum controlled-phase gate with tunable phase shift. This gate belongs among a set of prominent quantum gates that can constitute a quantum computer. Our implementation is based on an optimal design. We have published our finding in Physical Review Letters. Subsequently we have published a number of papers discussing the gate’s properties in more detail.

Invited talks

  • K. Lemr et al., “Linear-optical quantum routers,” QEINO 2013, Poznan (Poland)
  • K. Lemr et al., “Optimal linear-optical tunable controlled phase gate and related research,” QEIB 2012, Poznan (Poland)
  • K. Lemr et al., “Quantum information in the Joint Laboratory of Optics – last three years of photon pairs,” QEIB 2012, Poznan (Poland)
  • K. Lemr “Quantum information processing in Olomouc,” Notre Dame University 2010, Indiana (USA)

International collaboration

Poland dr. Karol Bartkiewicz

Adam Mickiewicz University, Poznan (Poland)

prof. Pawel Horodecki

Nat. Quant. Inf. Cent. in Gdansk (Poland)

prof. Karol Zyczkowski

Polish Academy of Sciences (Poland)

dr. Magdalena Stobinska

University of Gdansk (Poland)

Japan prof. Adam Miranowicz

RIKEN (Japan)

prof. Franco Nori

RIKEN (Japan)

Canada prof. Thomas Jennewein

University of Waterloo (Canada)

dr. Evan Meyer-Scott

University of Waterloo (Canada)

Germany prof. Jens Eisert

University of Potsdam (Germany)

dr. Konrad Kieling

University of Potsdam (Germany)

Italy prof. Maria Bondani

CNISM UdR Como (Italy)

dr. Alessia Allevi

CNISM UdR Como (Italy)

Selected grant projects

  • Linear-optical quantum controlled phase gate and its applications (Czech Science Foundation, 2013 – 2015), principal investigator
  • Research centre – Optical structures, detection systems and related technologies for low photon-number applications (1M06002, Czech Ministry of Education, 2006 – 2011)
  • Coherence and non-linear optics – selected chapters (Internal grant by Palacky University, 3/2010 – 2/2011), principal investigator
  • Preparation of experimental educational course in quantum and non-linear optics (Czech Ministry of Education, 2011), principal investigator


  • SLO/BEM3, SLO/BENF – Experimental methods for nanophotonics
  • SLO/BZDF – Sources and detectors for nanophotonics
  • SLO/ZF1 – Fundamentals of photonics 1
  • SLO/FTB – Physical theory of colours

Supervised theses

  • Marek Bula: Construction and design of devices for quantum information processing (master’s thesis, in progress)
  • Vojtěch Trávníček: Characterisation of a stream camera (bachelor’s thesis, in progress)
  • Jiří Beran: Analysis of the tunable controlled-phase gate (bachelor’s thesis, in progress)
  • Richard Jusku: Time-resolved spectroscopy of selectid isomers of organic compounds (bachelor’s thesis, in progress)
  • Marek Bula: Construction of fibre Mach-Zehnder interferometer using fibre couplers with tunable splitting ratios (bachelor’s thesis, defended 2012)