Cirac Group

We carry out theoretical research in Quantum Optics, Quantum Information, and Quantum Many-Body Physics.

Quantum Optics

Quantum dots coupled to a spin environment.
Levitating spheres.

In Quantum Optics, we investigate how microscopic systems can be controlled and manipulated at the quantum level using external fields, and how such systems can be scaled up in a controlled way. We propose experiments that aim at observing interesting quantum phenomena, and develop specific theoretical tools for the problems at hand. We also develop proposals that use atomic systems for the quantum simulation of e.g. condensed matter or high energy physics models. The systems we explore include atoms in optical lattices, trapped ions, quantum dots, but also novel platforms (levitating spheres, nanoplasmonic lattices, NV-centers in diamond), hybrid systems and the use of engineered dissipation.

Quantum Information Theory

Study of the computational power of quantum computing.

We also participate in the development of a theory of Quantum Information, which will be the basis of the applications in the world of communication and computation once microscopic systems can be controlled at the quantum level. This includes the study of the computational power of quantum computing, and which quantum states and computations can be simulated classically, but also the design of new quantum algorithms and quantum memories. In the field of quantum communication, we are concerned with the security of quantum key distribution schemes and the preparation of long-range entanglement, necessary for the construction of quantum networks. Our group also investigates questions related to Quantum Foundations, which aim at testing Quantum Mechanics itself. In particular we investigate macroscopic realism, as well as the possibilities of macroscopic superpositions.

Condensed Matter Physics

PEP tensor network to analyze the dynamics of a quantum many-body system.
Phase diagram of a quantum spin model.

Another main research line consists of applying the ideas of Quantum Optics and Quantum Information to other disciplines, in particular to Condensed Matter Physics and the study of Quantum Many-Body Systems. A central tool are tensor networks, such as PEPS or MERA, with which we explore fermionic systems, mixed states, quantum field theories (with continuous MPS), and conformal field theories (with infinite MPS). We use them to theoretically characterize topological phases, classify the phases of matter, do renormalization group theory, establish a bulk-boundary correspondence and find parent Hamiltonians for states of interest. We also use them numerically to explore dynamical properties, anyonic excitations, and investigate High Energy Physics models. Finally, we also investigate phase diagrams of quantum spin models (Fig. 5) and analyze specific models.

Prof. J. Ignacio Cirac


Max Planck Institute for Quantum Optics
Hans-Kopfermann-Str 1
D-85748 Garching


Andrea Kluth
Phone: +49 (0)89 / 3290 - 5736
Fax: +49 (0)89 /
3290 - 5336

Group webpage