Long-lived Qubits at room temperature
From more efficient database queries to the cracking of today's reliable cryptographic systems: The development of a competitive quantum computer would mark the beginning of a new digital era. So far research is focused on finding suitable processing units, the so-called quantum bits (qubits). In contrast to classical bits, they cannot only be in the states 0 and 1, but also in an arbitrary superposition of those two states. A prerequisite for useful computations is a long coherence time (life time) of the superposition states. Prof. Joris van Slageren´s research group at the Institute of Physical Chemistry, University of Stuttgart recently published results on a coordination compound with exceptionally long coherence times over an unusually wide temperature range in Nature Communications.
Bader, K. et al. Room temperature quantum coherence in a potential molecular qubit. Nat. Commun. 5:5304 doi: 10.1038/ncomms6304 (2014).
Recently, many different systems have been proposed for the physical implementation of a quantum bit. Very promising proposals utilize the electron spin in magnetic molecules.
Of these, coordination compounds consisting of a metal ion with organic groups (ligands) offer the advantage of the realization of tailor-made physical properties via convenient chemical manipulations.
A well-known limiting factor for the life time of the superposition state is the presence of adjacent nuclear spins, as they generate stray fields. Based on this knowledge the Van Slageren group identified a compound containing very few nuclear spins in vicinity of the electron spin as potential candidate for showing long coherence times.
The compound consists of a central copper ion incorporated in an organic shell with only few nuclear spin carrying elements. Additionally, the ligand shell is very flat and rigid which enables the compound to form stable columns in the solid state.
The measurements of Van Slageren´s research group proved that these design-criteria indeed enable exceptionally long coherence times. At low temperatures (7 Kelvin) a coherence time of 68 microseconds was observed. This substantially exceeds previous reported values for molecular compounds, which were around a few microseconds.
Astonishingly, the Stuttgart researchers were able to detect coherence over an unusually wide temperature range. So far molecular qubits only showed coherence at very low temperatures, whereas the introduced compound´s coherence is room-temperature stable. With this property, the realization of energy efficient quantum computers with low operating expenses moves closer.
The next challenge on the way towards a working quantum computer is the structured deposition of the compound on surfaces, which will be tackled now by the Stuttgart researchers. “In order to construct a quantum computer it´s not only necessary to identify compounds with long coherence times, but also to find a possibility for selectively addressing them” says Ph.D.-student Katharina Bader.
The work is part of her doctoral dissertation, which is supported by “Fonds der Chemischen Industrie”. The measurements were performed in cooperation with Goethe University Frankfurt and were financially supported by “Deutsche Forschungsgemeinschaft” and “Center for Integrated Quantum Science and Technology (Stuttgart/Ulm)”.
Prof. Joris van Slageren, Universität Stuttgart, Institut für Physikalische Chemie, Tel. 0711/685-64380,
E-Mail: slageren (at) ipc.uni-stuttgart.de
Andrea Mayer-Grenu, Universität Stuttgart, Abt. Hochschulkommunikation, Tel. 0711/685-82176,
E-Mail: andrea.mayer-grenu (at) hkom.uni-stuttgart.de
Andrea Mayer-Grenu | idw - Informationsdienst Wissenschaft
Information integration and artificial intelligence for better diagnosis and therapy decisions
24.05.2017 | Fraunhofer MEVIS - Institut für Bildgestützte Medizin
World's thinnest hologram paves path to new 3-D world
18.05.2017 | RMIT University
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
29.05.2017 | Earth Sciences
29.05.2017 | Life Sciences
29.05.2017 | Physics and Astronomy