Current Topics of Interest
|
Quantum Thermodynamics (QT) is concerned with the investigation of phenomena such as thermalization and equilibration, heat engines, and foundations of thermodynamics in the quantum regime.The study of thermodynamics in the quantum domain provides an amazing example for the cross-fertilization between different areas of physics, involving classical thermodynamics and solid state physics, as well as quantum information and quantum field theory. For recent reviews see [Goold, Huber, Riera, del Rio, Skrzypczyk, J. Phys. A: Math. Theor. 49, 143001 (2016)], [Vinjanampathy, Anders, Contemp. Phys. 57, 1 (2016)] and [Millen, Xuereb, New J. Phys. 18, 011002 (2016)].
My current reseach interest within QT lies in fundamental and practical restrictions for thermodynamic processes in quantum optics. In particular, I am interested in learning about the usefulness (and restrictiveness) of Gaussian operations for tasks such as energy extraction, storage, and distribution, as well as converting work and correlations into each other. More information can be found here. |
|
|
Quantum metrology exploits distinctive quantum features, such as entanglement, to enhance the estimation precision of parameters governing the dynamical evolution of the probe systems beyond that achievable by classical means. This enhancement is manifested in the form of a scaling gap in precision with respect to the available resources (the number of probe systems or the average input energy) between the corresponding optimal quantum and classical strategies, and depends on the specific encoding of the parameter in the Hamiltonian describing the evolution.
Here, I have recently been pursuing the question, whether architectures for measurement-based quantum computation can be employed as flexible metrology devices. In this context, we have recently investigated the possibility of creating a versatile all-purpose device for quantum metrology based on 2D cluster states [Friis, Orsucci, Skotiniotis, Sekatski, Dunjko, Briegel, Dür, New J. Phys. 19, 063044 (2017)]. A presentation of this work can be found here (pdf). |
Cluster states for metrology: Sacrificing some qubits for the preparation (green) of a probe state for sensing (purple), and some qubits for implementing optimal measurements (orange), a metrological scaling advantage in precision can be obtained for different metrology scenarios.
|
Another research interest in quantum metrology concerns estimation scenarios where the parameter of interest is encoded in Gaussian transformations, see [Friis, Skotiniotis, Fuentes, Dür, Phys. Rev. A 92, 022106 (2015)], and more generally in the connection between quantum metrology, quantum computing and quantum thermodynamics.
For more information see this page.
For more information see this page.
|
An interesting connection between quantum computing and artificial intelligence arises from modelling the decision-making processes of autonomous learning agents via quantum random walks. The framework for this investigation is the Projective Simulation (PS) model, introduced in [Briegel, De las Cuevas, Sci. Rep. 2, 400 (2012)], and its variant the Reflecting Projective Simulator [Paparo, Dunjko, Makmal, Martín-Delgado, Briegel, Phys. Rev. X 4 031002 (2014)]. A key element in the computational architecture that allows the agent to update its decision-making process when it learns is coherent controlization, i.e., a method of adding control to a set of a priori unspecified unitaries. We have investigated these methods for systems of trapped ions [Dunjko, Friis, Briegel, New J. Phys. 17, 023006 (2015)] and superconducting qubits [Friis, Melnikov, Kirchmair, Briegel, Sci. Rep. 5, 18036 (2015)]. More information can be found on this website.
|
|
|
Fermions make up essentially all standard matter in the standard model of particle physics, but interestingly their role in quantum information and computation is sometimes regarded as marginal. Nonetheless, growing interest in fermions and their interesting properties is arising through applications in solid state physics. Many theoretical studies rely on mappings between fermions and qubits - the Pauli principle practically limits the occupation of a fermionic mode to at most one particle, effectively turning them into two-level systems. However, there is an interesting mismatch between fermions and qubits. My research interest is hence to study this difference, to learn in what sense "fermions are not qubits", and to study the quantum correlations in fermionic systems with no fixed particle number. Read about it in [Friis, Lee, Bruschi Phys. Rev. A 87, 022338 (2013)], and in [Friis, Reasonable fermionic quantum information theories require relativity, New J. Phys. 18, 033014 (2016)], or in our recent article on fermionic teleportation [Debarba, Iemini, Giedke, Friis, Phys. Rev. A 101, 052326 (2020)]. Download a presentation [pdf], or find out more on this website.
|
|
