AG Eisert

Quantum many-body theory, quantum information theory, and quantum optics

Prof. Dr. Jens Eisert

Dahlem Center for Complex Quantum Systems

Research

Our group is concerned with research in quantum information theory, quantum optical implementations of quantum information ideas, and quantum many-body theory.

• We ask what information processing tasks are possible using single quantum systems as carriers of information. On the one hand, we think about the mathematical-theoretical foundations of quantum information, specifically about the theory of entanglement.
  
• On the other hand, we are involved in identifying quantum optical realizations of such ideas, specifically using light modes or cold atoms in optical lattices.
  
• A main emphasis of our theoretical research is on the theory of quantum systems with many degrees of freedom, particularly in the condensed matter context, concerning their static properties, their efficient numerical simulation, as well as their quantum dynamics in non-equilibrium.

Characteristic for our work is to be guided by the rigor of mathematical physics, but at the same time be pragmatically and physically motivated, which often leads to collaborations with experimentalists.

Non-equilibrium dynamics of quantum many-body systems

• "Probing the relaxation towards equilibrium in an isolated strongly correlated 1D Bose gas",
  Nature Physics 8, 325 (2012).
• "Thermalization in nature and on a quantum computer",
  Phys. Rev. Lett. 108, 080402 (2012).
• "Absence of thermalization in non-integrable systems",
  Phys. Rev. Lett. 106, 040401 (2011).
• "A dissipative Church Turing theorem",
  Phys. Rev. Lett. 106, 010403 (2011).
• "Supersonic quantum communication",
  Phys. Rev. Lett. 102, 240501 (2009).
  

Quantum information theory

• "Entangled inputs cannot make imperfect channels perfect",
  Phys. Rev. Lett. 106, 230502 (2011).
• "Experimental implementation of the optimal linear-optical controlled phase gate",
  Phys. Rev. Lett. 106, 013602 (2011).
• "Most quantum states are too entangled to be useful as computational resources",
  Phys. Rev Lett. 102, 190501 (2009).
• "Entanglement combing",
  Phys. Rev. Lett. 103, 220501 (2009).
• "Entangled families", News and Views,
  Nature 455, 180 (2008).
  

Quantum system identification, compressed sensing, and tomography

• "Extracting dynamical equations from experimental data is NP-hard",
  Phys. Rev. Lett. 108, 120503 (2012).
• "Quantum tomography via compressed sensing: error bounds, sample complexity, and efficient estimators",
  New J. Phys. 14, 095022 (2012).
• "Directly estimating non-classicality",
  Phys. Rev. Lett. 106, 010403 (2011).
• "Quantum state tomography via compressed sensing",
  Phys. Rev. Lett. 105, 150401 (2010).
  

Tensor network approaches to solving condensed matter models

• "Wick's theorem for matrix-product states",
  Phys. Rev. Lett. 110, 040401 (2013).
  "Solving frustration-free spin models",
  Phys. Rev. Lett. 105, 060504 (2010).
• "Real-space renormalization yields finite correlations",
  Phys. Rev. Lett. 105, 010502 (2010).
• "Holographic quantum states",
  Phys. Rev. Lett. 105, 260401 (2010).
• "Unitary circuits for strongly correlated fermions",
  Phys. Rev. A 81, 050303(R) (2010).

Mathematical physics

• "The complexity of relating quantum channels to master equations",
  Commun. Math. Phys. 310, 383 (2012).
• "Concentration of measure for quantum states with a fixed expectation value",
  Commun. Math. Phys. 303, 785 (2011).
• "The Gaussian quantum marginal problem",
  Commun. Math. Phys. 280, 263 (2008).
  

Correlations in quantum many-body systems

• "Area laws for the entanglement entropy",
  Rev. Mod. Phys. 82, 277 (2010).
  

Quantum optics

• "Gaussification and entanglement distillation of continuous-variable systems: A unifying picture",
  Phys. Rev. Lett. 108, 020501 (2012).
• "Tomography of quantum detectors",
  Nature Physics 5, 27 (2009).
  

Open quantum systems and opto-mechanics

• "Cooling by heating",
  Phys. Rev. Lett. 108, 120602 (2012).
• "Gently manipulating opto-mechanical systems",
  Phys. Rev. Lett. 103, 213603 (2009).
• "Assessing non-Markovian dynamics",
  Phys. Rev. Lett. 101, 150402 (2008).
  

For more recent publications and a complete list of older publications, see this link.