Working Group Quantum Spin Circuits

Head: Prof. Dr. Wolfgang Wernsdorfer

Our endeavour is driven by one of the most ambitious technological goals of today’s scientists: the realization of an operational quantum computer, or more general, the development of devices working on the principles of quantum mechanics. In this regard, the basic building block is generally composed of a two-level quantum system, namely a quantum bit (or qubit). Such a quantum system must be fully controllable and measurable, which requires a connection to the macroscopic world. In this context, solid-state devices, which establish electrical interconnections to the qubit, are of high interest, mainly due to the variety of methods available for the fabrication of complex and scalable architectures. Moreover, outstanding improvements in the control of the qubit dynamics have been achieved in the last years.

We are building a unique platform for low-temperature research, with a focus on molecular quantum spintronics, but other subjects are also studied. Our scientific approach uses the superior flexibility of chemistry, concerning tuning, controlling and manipulating the properties of the molecules (spin, anisotropy, redox potential, light, electrical field...), which can lead to breakthroughs in the field of quantum electronics. We fabricate high-quality devices by depositing magnetic molecules in UHV condition and by in-situ characterization/manipulation of the molecule/device assembly using AFM/STM techniques. We explore the quantum properties of these molecules via a hybrid coupling to (i) a quantum dot (ligand, carbon nanotube), (ii) a quantum nanomechanical system, (iii) an optically active ion (NV centres in diamond, etc.), (iv) a superconducting device, and (v) a silicon-based CMOS device. Firstly, the hybrid coupling is used as an amplifier to read out efficiently the spin states of the molecule, minimizing back action from the environment on the spin system and thereby preserving the quantum states. Secondly, it allows us to entangle both systems in order to study new effects, which are intrinsic to the hybrid systems, for example, non-classical states of motion. This could lead to a better understanding of quantum mechanics, new phenomena and applications.

The visionary concept of encoding quantum bits within magnetic molecules is underpinned by worldwide research on molecular magnetism and supramolecular chemistry, within the European Institute of Molecular Magnetism. Supramolecular chemistry will provide different, powerful, and cheap tools and procedures to engineer and assemble quite complex molecular devices, allowing proof-of-principle experiments on a “molecular quantum processor”. The main target for the coming years is fundamental science, with a view on applications in quantum electronics.

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Members (in alphabetical order)
Name Tel
Bld.-Room E-Mail
viktor adamGgn9∂kit edu
safa.ahmedGgn9∂kit edu
tino cubaynesGgn9∂kit edu
simon guenzlerGgn9∂kit edu
daria sostinaGgn9∂kit edu
wolfgang wernsdorferGgn9∂kit edu