Low temperature record published in APL as an Editor's pick, with Scilight!Image: A Coulomb blockade thermometer on a nuclear demagnetization stage.

Low temperature record published in APL as an Editor's pick, with Scilight!Image: A Coulomb blockade thermometer on a nuclear demagnetization stage.

Hyperfine-phonon spin relaxation paper appeared on arXiv, reporting spin lifetimes of up to one minute in a GaAs single electron quantum dot

Welcome the new Bluefors XLD dry fridge to the team!

The Quantum Coherence Lab has a new Homepage!

- Startseite
- News

Dr. Arne Laucht, University of New South Wales, Sydney, Australia, just gave a special seminar "*Silicon quantum processor unit cell operation above one Kelvin*". Thanks very much for the visit and a very interesting talk...

Prof. Carlos Egues, Sao Paulo University, Brazil, is currently visiting the group this week and just gave a special seminar about "Many-body localization in a central spin model". Thanks very much for giving a very interesting talk on a topic which we enjoyed very much to learn more about...

Prof. Catalina Marinescu, Clemson University, USA, gave a special seminar about "*Localization in Spin-Orbit Coupled Electron Systems". *Thanks for giving a very nice paedagogical presentation, from the basics of weak-localization physics to the new, break-through result: analytical closed-form solution for general Rashba-Dresselhaus* *coupled semiconductor quantum wells, as presented in our PRL112, 156601 (Apr 2019). * *

Call open for 39 doctoral fellowships on Quantum Science and Technologies on EUCOR -- The European Campus through MSCA COFUND H2020 Trinational Doctoral Program.

Apply now, call closes Aug 19, 2019.

More information https://www.eucor-uni.org/en/qustec/application-information/apply/

Our international team characterizes the quality of remote hydrogen plasma defined graphene edges by Raman spectroscopy, atomic resolution AFM and low temperature electronic transport measurements. For graphene on hBN, the edge is ~40% zigzag and ~60% armchair-30 degree segments, while overall running in the zigzag direction. Rehmann, Kalyoncu et al., Carbon 150, 417 (May 24, 2019).

Riken-UCSB-Basel collaboration extracts full 3D-confinement parameters and in-plane orientation of the single-electron quantum orbitals of a GaAs gate-defined dot with sub-nm precision. This is a versatile tool for quantum dots with one dominant axis of strong confinement. Camenzind, Yu et al., Phys. Rev. Lett. 122, 207701 (May 22, 2019). * Editors' Suggestion *and featured with viewpoint in Physics. See also UniNews.

This is theoretical work lead by Catalina Marinescu, Clemson University, and J. Carlos Egues, Sao Paulo University, with experiments by Pirmin Weigele and Dominik Zumbühl, University of Basel. We have derived a closed-form expression for the weak localization corrections to the magnetoconductivity of a 2D electron system such as a GaAs quantum well with arbitrary Rashba and both linear and cubic Dresselhaus spin-orbit interactions in a perpendicular magnetic field geometry. Marinescu et al., Phys. Rev. Lett. 122, 156601 (Apr 18, 2019).

Today, Prof. Seigo Tarucha from the RIKEN lab and the Unviersity of Tokyo, Japan, is giving the Basel Physics Colloquium with the title "Physics and Technology of Spin-based Quantum Computing with Quantum Dots". From dots in GaAs to Si, Si/Ge and finally to isotopically purified Si spins reaching fidelities >99%... very impressive results! Thanks very much for the inspiring visit!

Leon Camenzind successfully defended his PhD thesis "Spins and Orbits in Semiconductor Quantum Dots" today, getting a summa cum laude, with Prof. Seigo Tarucha, RIKEN and University of Tokyo, Japan, as coreferee and Prof. Daniel Loss as chair. Congratulations, Leon, on a great thesis, and thanks very much for all the work!

We investigate the quality of remote hydrogen plasma defined graphene edges by Raman spectroscopy, atomic resolution AFM and low temperature electronic transport measurements. While on graphite substrate, the edges seem to be nearly perfect zigzag termination, for graphene on hBN, we find the edge consists of about 40% zigzag and about 60% armchair-30 degree segments, while overall running in the zigzag direction. Hence, further optimization of the hydrogen plasma etching technique is required to obtain higher quality zigzag graphene edges. arXiv:1903.07002

**Research** focuses on quantum transport experiments investigating quantum coherence, electron spins and nuclear spins and interactions in semiconductor and graphene nanostructures. Ongoing projects include

- spin qubits in coupled, laterally gated GaAs quantum dots
- microkelvin temperatures in nanoscale sample
- novel quantum states of matter, such as electron or nuclear spin helices, topological states and Majorana fermions
- spin-orbit coupling in GaAs quantum wells
- experiments investigating mesoscopic electron transport, including graphene nanoribbon research

We are interested in coherent manipulation of individual quantum systems in solid state nanostructures with quantum computation as a long term goal.

**Experiments** investigate quantum transport through semiconductor nanostructures which are fabricated in house using high mobility 2D electron gas materials obtained from collaborating molecular beam epitaxy labs. Experiments are typically performed in dilution refrigerators at millikelvin temperatures in magnetic fields. Measurements are done using electronic low-noise techniques and may involve nanosecond-pulsing and microsecond readout schemes.

An ERC Starting Grant from the first ERC call was awarded to our group and boosted our research from 2008-2013 (press release)

Positions are currently available, please see the positions page.

We are affiliated with

- Department of Physics, University of Basel
- Swiss Nanoscience Institute (SNI)
- Basel QC2 Center for Quantum Computing and Quantum Coherence
- Harvard Nanoscale Science and Engineering Center (NSEC) of the US National Science Foundation and
- NCCR Quantum Science and Technology - NCCR QSIT of the Swiss NSF. QSIT video

Our group enjoys numerous ongoing collaborations, including the following groups (in arbitrary order)

- Schönenberger group, Basel (nano-electronics, fabrication)
- Loss group, Basel (theory)
- Gossard group at UC Santa Barbara (MBE growth)
- Wegscheider group, ETH Zurich (MBE growth)
- Pfeiffer group, Princeton University (MBE growth)
- Yacoby group, Harvard University (GaAs quantum wires)
- Awschalom group, University of Chicago (persistent spin helix and spin-orbit coupling in GaAs quantum wells)
- Egues group, Sao Paulo University (theory)
- Pekola group, Aalto University, Helsinki (Coulomb blockade thermometry)
- Lancaster group (George Pickett), England (nuclear refrigeration)
- European microkelvin collaboration, ultra-low temperature physics and techniques (EU FP7 integrating activity)
- BaselCryogenics, Low temperature filtering and thermalization

23 Aug 13:15

1.09

Master Thesis Defense - Fabian

20 Sep 13:15

1.09

Master Thesis Defense - Simon Svab

11 Okt 13:15

1.09

Tim

18 Okt 13:15

1.09

Andreas

*Silicon quantum processor unit cell operation above one Kelvin*". Thanks very much for the visit and a very interesting talk...

*Localization in Spin-Orbit Coupled Electron Systems". *Thanks for giving a very nice paedagogical presentation, from the basics of weak-localization physics to the new, break-through result: analytical closed-form solution for general Rashba-Dresselhaus* *coupled semiconductor quantum wells, as presented in our PRL112, 156601 (Apr 2019). * *

Call open for 39 doctoral fellowships on Quantum Science and Technologies on EUCOR -- The European Campus through MSCA COFUND H2020 Trinational Doctoral Program.

Apply now, call closes Aug 19, 2019.

More information https://www.eucor-uni.org/en/qustec/application-information/apply/

* Editors' Suggestion *and featured with viewpoint in Physics. See also UniNews.

**Research** focuses on quantum transport experiments investigating quantum coherence, electron spins and nuclear spins and interactions in semiconductor and graphene nanostructures. Ongoing projects include

- spin qubits in coupled, laterally gated GaAs quantum dots
- microkelvin temperatures in nanoscale sample
- novel quantum states of matter, such as electron or nuclear spin helices, topological states and Majorana fermions
- spin-orbit coupling in GaAs quantum wells
- experiments investigating mesoscopic electron transport, including graphene nanoribbon research

We are interested in coherent manipulation of individual quantum systems in solid state nanostructures with quantum computation as a long term goal.

**Experiments** investigate quantum transport through semiconductor nanostructures which are fabricated in house using high mobility 2D electron gas materials obtained from collaborating molecular beam epitaxy labs. Experiments are typically performed in dilution refrigerators at millikelvin temperatures in magnetic fields. Measurements are done using electronic low-noise techniques and may involve nanosecond-pulsing and microsecond readout schemes.

An ERC Starting Grant from the first ERC call was awarded to our group and boosted our research from 2008-2013 (press release)

Positions are currently available, please see the positions page.

We are affiliated with

- Department of Physics, University of Basel
- Swiss Nanoscience Institute (SNI)
- Basel QC2 Center for Quantum Computing and Quantum Coherence
- Harvard Nanoscale Science and Engineering Center (NSEC) of the US National Science Foundation and
- NCCR Quantum Science and Technology - NCCR QSIT of the Swiss NSF. QSIT video

Our group enjoys numerous ongoing collaborations, including the following groups (in arbitrary order)

- Schönenberger group, Basel (nano-electronics, fabrication)
- Loss group, Basel (theory)
- Gossard group at UC Santa Barbara (MBE growth)
- Wegscheider group, ETH Zurich (MBE growth)
- Pfeiffer group, Princeton University (MBE growth)
- Yacoby group, Harvard University (GaAs quantum wires)
- Awschalom group, University of Chicago (persistent spin helix and spin-orbit coupling in GaAs quantum wells)
- Egues group, Sao Paulo University (theory)
- Pekola group, Aalto University, Helsinki (Coulomb blockade thermometry)
- Lancaster group (George Pickett), England (nuclear refrigeration)
- European microkelvin collaboration, ultra-low temperature physics and techniques (EU FP7 integrating activity)
- BaselCryogenics, Low temperature filtering and thermalization

23 Aug 13:15

1.09

Master Thesis Defense - Fabian

20 Sep 13:15

1.09

Master Thesis Defense - Simon Svab

11 Okt 13:15

1.09

Tim

18 Okt 13:15

1.09

Andreas