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
NASA CubeSat to test miniaturized weather satellite technology
10.11.2017 | NASA/Goddard Space Flight Center
New approach uses light instead of robots to assemble electronic components
08.11.2017 | The Optical Society
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses