Exploring spin coherence of a single atom: finding a (quantum needle) in a haystack

A team of scientist from the IBM Research Lab at Almaden (San Jose, USA), the IBS-QNS -Institute for Basic Science, Center for Quantum Nanoscience (Seoul, Korea) and the QuantaLab,  INL has been able to carry out a magnetic resonance experiment that probes an individual magnetic atom. This permits them to probe, at the atomic scale, “quantum coherence”, an essential resource in the so called quantum technologies.

Magnetic resonance is a technique that permits to obtain information about biological tissues from the measurement of the magnetic behaviour of atomic nuclei. In a conventional magnetic resonance measurement, such as those carried out at hospitals, it is necessary to integrate the signal coming from, at least, a trillion (1012) atoms.

Being able to probe a individual magnetic atom, is very exciting”, says Joaquín Fernández-Rossier (QuantaLab-INL , a theoretical physicist involved in the work, “this finding provides a deeper understanding of one of the main challenges that we are facing to build quantum computers, namely, to extend the lifetime of quantum coherence”.

These findings have been reported in the prestigious journal Science Advances, edited by the American Association for the Advancement of Science, on February 16 2018.

Magnetic resonance and quantum coherence. In a conventional magnetic resonance experiment, atoms are prepared in a quantum state in which their magnetic moments is pointing out, at the same time, in two opposite directions. The phenomenon that enables the existence of this type of state, impossible at the macroscopic scale, is known as quantum coherence. In their experiment, the research team was able to measure the lifetime of the quantum coherence of an individual atom.

Mechanism of loss of coherence. In this case, the resonance experiment entails electrical current going through the individual atom. In other words, the atom is being bombarded by electrons.The pace at which this happens determines the lifetime of the aforementioned coherent superposition state: the larger the current, the shorter the lifetime of the quantum coherence.

A microscope to “see” atoms. The tool that makes this experiment possible is the Scanning Electron Tunnelling Microscope, that contains a sharp metallic tip that is approached to the atoms of surface, in ultra-high vacuum and very low temperatures. This tool, used in many labs to visualise individual atoms, in a way that resembles the way visually impaired people uses a white cane, can in addition be used to excite and detect the magnetic resonance of individual atoms.

An ongoing collaboration.  This work is part of an ongoing collaboration between  the teams at IBM Almaden,  QNS-IBS and  the group of J. Fernández-Rossier at QuantaLab-INL.  A few months after another publication in Physical Review Letters, where the same team demonstrated the manipulation of couples of atoms on a surface, using the same technique

Probing quantum coherence in single-atom electron spin resonance
P. Willke, W. Paul, F. D. Natterer, K. Yang, Y. Bae, T.Choi, J. Fernández-Rossier,, A. J. Heinrich, and C. P. Lutz
SCIENCE  ADVANCES  : Vol. 4, no. 2, eaaq1543 FEB 16  2018

Engineering the Eigenstates of Coupled Spin-1/2 Atoms on a Surface
Yang, Kai; Bae, Yujeong; Paul, William; et al.
PHYSICAL REVIEW LETTERS Volume: 119 Issue: 22 Article Number: 227206 Published: NOV 29 2017




Scheme of the experimental setup. An STM tip (grey balls) is placed on top of an individual iron (Fe) atom, placed on a surface. Reproduced from Science Advances

QuantaLab Workshop 2017


QuantaLab workshop 2017

QuantaLab workshop 2017, will take place next September 12 &13 at INL (Braga, Portugal).  The workshop is open for participation of QuantaLab members as well as a limited amount of  external participants.


The workshop will cover several topics within the broad interests of QuantaLab (quantum technologies and quantum materials), with emphasis in 2D  materials ( electronically ordered phases, synthesis, optical properties, and their potential application in quantum technologies).

Link to Complete program and schedule

Confirmed Invited Speakers:

  • Pablo Alonso (U. Oviedo, Spain)
  • Andrés Castellanos-Gómez (ICMM-CSIC, Spain)
  • Marcos Curty ( U. Vigo, Spain)
  • Eunézio Antônio de Souza (MackGraphene Research Centre, Brazil)
  • Andrés Gómez  (CESGA, Spain)
  • Dmitri Efetov (ICFO, Spain)
  • Antía Lamas Linares (TACC, UT Austin, USA)
  • Miguel Moreno Ugeda (CIC Nanogune, Spain)
  • Thomas Pedersen (Aalborg University, DK)
  • Francisco Rivadulla (U. Santiago, Spain)


  • Joaquín Fernández Rossier (INL)
  • Nuno M. R. Peres (UM)


Registration in the workshop, filling the form below,  is required.

Registration Deadline:  August 15st



QuantaLab seminar “1D physics in metallic line defects of the semiconductor MoSe2”

Next  May 16, Tuesday,  at 10:30 we have a QuantaLab Seminars at the INL conference room.

1D physics in metallic line defects of the semiconductor MoSe2

 Professor J. M. P. Carmelo1, 2

 (1) Department of Physics, University of Minho, P-4710-057 Braga, Portugal

(2) Center of Physics of University of Minho and University of Porto, P-4169-007 Oporto, Portugal


Material line defects in the 2D van der Waals layered semiconductor MoSe2 are 1D structures [1]. Quantum wires and junctions can be isolated in line defects of other transition metal dichalcogenides, which may enable quantum transport measurements and devices.

At low temperatures our scanning tunnelling microscopy and angle resolved photoemission spectroscopy studies find a charge-density wave state for the MoSe2 twin-grain boundaries and that at T _ 300K they exhibit features characteristic of a 1D metal. Our theoretical study uses a pseudofermion representation that was originally introduced for 1D integrable correlated quantum problems [2,3]. The universality of some properties in both integrable and non-integrable 1D correlated models [1] allows the use of such a representation for finite-energy ! windows in the vicinity of the cusps of the one-particle spectral function of non-integrable correlated problems, which are extensions of corresponding integrable models. Specifically, we use that universality to generate from the pseudofermion dynamical theory of the conventional 1D Hubbard model [3] a corresponding renormalised theory for that model with additional electron finite-range interactions [1]. The experimental spectral line splits into distinctive spin-like and charge-like spectral features. Their dispersions and (k, w)-plane weight distributions are found to exactly follow those predicted by the non-integrable 1D Hubbard model with suitable electron finite-range interactions associated with the exponent _ _ 0.78 found experimentally for the density of states suppression, |!|_.


[1] Y. Ma, H. C. Diaz, J. Avila, C. Chen, V. Kalappattil, R. Das, M.-H. Phan, T. ˇCadeˇz, J. M. P. Carmelo, M. C. Asensio, and M. Batzill
Nature Communications 8, 14231 doi: 10.1038/ncomms14231 (2017).

Open access in http://www.nature.com/articles/ncomms14231


[2] J. M. P. Carmelo and T. Prosen
Nuclear Physics B 914, 62-98 (2017).

Open access in http://www.sciencedirect.com/science/article/pii/S0550321316303492

[3]  J. M. P. Carmelo and T. ˇCadeˇz
Nuclear Physics B 914, 461-552 (2017).

Open access in http://www.sciencedirect.com/science/article/pii/S0550321316303595

INL new Group Leader, Zhongchang Wang

Zhongchang Wang, formerly associate professor in Tohoku University, started on March 1st as Senior Staff Researcher at INL. Zhongchang is going to  lead the newly established  group of Atomic Manipulation for Quantum Nanotechnology, at INL.   He is going to work on structure-property interplay of two-dimensional materials and nanomaterials at the atomic scale so as to fulfill atomic manipulation of quantum nanostructures through combining electron microscopy, spectroscopy, first-principles calculations and property assessment.

Zhongchang Wang received a Master degree from Chongqing University in China (2004) and a Ph. D. in materials science and engineering from the University of Tokyo in Japan (2007) where he worked on elucidation of switching meachism of atomic switches. He thereafter spent two years (2008-2009) as a postdoctoral research associate at Advanced Institute for Materials Research, Tohoku University (Japan) and subsequently three years (2010-2013) as an assistant professor in the same institution. In 2013, he was promoted to associate professor at Advanced Institute for Materials Research, Tohoku University. In 2016, he was also a visiting scientist at University College London (UCL), UK. In Tohoku University, he conducted both experiments and first-principles calculations with a special attention on defects and interfaces in functional materials and on how they mediate material property shift at atomic scale, aimed at tackling fundamental material issues in a broad range of functional material systems. He has made contribution to the fields of atomic structures of materials, phases and interfaces and their correlation with physico-chemical properties by merging the state-of-the-art (scanning) transmission electron microscopy with density-functional theory calculations. He has received a total of 17 research grants from Japanese government and companies, and (co-) authored over 180 peer-reviewed SCI-indexed papers in Nature, Nat. Nanotech., Nat. Commun. Adv. Mater., Angew Chemie, Phys. Rev., Appl. Phys. Lett. etc. Moreover, he has also delivered over 30 invited talks in international conferences and received several awards from Japan and USA.



Seminar March 2: Towards Next Generation of Computing, Dr. Walter Riess

The QuantaLab is organising a talk by  Dr. Walter Riess –Head of the Science & Technology department at IBM Research – Zurich.
When:  next March 2 (2017),  Thursday,  at 11h

TITLE: Towards Next Generation of Computing

ABSTRACT: In the past decades the evolution of Information Technology has been governed by an exponential growth (Moore’s law) enabling continued economic, social and even political disruptions. However, as Moore’s law fades, progress will be less metronomic, nevertheless computers and other devices will continue to become more powerful. In my talk I will give brief insights towards the future of computing, addressing recent and future developments in conventional computing and new computing paradigms (neuromorphic & quantum computing).

Dr. Walter Riess is Head of the Science & Technology department at IBM Research – Zurich and coordinator of the Binnig and Rohrer Nanotechnology Center. The Zurich laboratory is home to world-class scientists representing more than 45 nationalities. Cutting-edge research and outstanding scientific achievements — including two Nobel Prizes — are associated with this Lab. The research activities of the Science & Technology department include future device concepts, quantum computing, personalized medicine, mobile health, human body data interfaces and nanotechnology.
Dr. Riess studied physics at the University of Bayreuth, Germany, where which he earned a Ph.D. in 1991 and habilitated in 1996. From 1991 to 1995, he led the Polymeric Light-Emitting Device group of Experimental Physics II at the University of Bayreuth. In 1995, he joined the IBM Research – Zurich Laboratory as a research staff member working on organic light-emitting diodes (LED). In 1998, he became manager of the Display Technology group working on display applications of electroluminescent organic materials, which today are game-changing technologies used in many television displays and mobile devices.
Dr. Riess has received numerous IBM awards and recognitions, among them the prestigious IBM Corporate Patent Portfolio Award in 2005. In 2007, he received a Special Recognition Award from the Society for Information Display for his leading contributions to the design and development of a top-emitting large-area active-matrix organic light-emitting display driven by amorphous silicon thin-film transistors. In 2014 he was named Distinguished Research Staff Member at IBM Research – Zurich.
Dr. Riess has authored and/or coauthored more than 100 scientific papers and holds 70 granted patents. He is a senior member of IEEE, member of the German Physical Society, the Swiss Physical Society, and the Materials Research Society.
Prior to his professional career, Dr. Riess was an internationally ranked judoka. In 1979, he won the bronze medal at the European Judo Championship in Brescia, Italy.

QuantERA Call 2017 Pre-Announcement


In January 2017 the QuantERA Consortium, coordinated by the National Science Centre (Poland), will announce a Call for Proposals in the field of quantum technologies.

Thematic scope of proposals should include one or more of the following areas:

  1. Quantum communication
  2. Quantum simulation
  3. Quantum computation
  4. Quantum information sciences
  5. Quantum metrology sensing and imaging
  6. Novel ideas and applications in quantum science and technologies

To know more go here.

Document with official  announcement. 

Workshop on Quantum Materials and Technologies, Santiago de Compostela, July 17-21 2017

The topical Solid State Group from the Spanish Royal Society of Physics, GEFES-RSEF,  will organize a 2-day symposium on “Quantum Materials and Technologies”  on July 18-19, 207,  at the RSEF biennial meeting that will take place in Santiago de Compostela on 17-21 July, 2017. The symposium will take

This symposium seeks to put together the rising concept of quantum materials, which comprises emergent phenomena in condensed matter physics, and quantum technologies, which aim to manipulate the quantum world for the development of conceptually new devices. Both topics are strongly related, for the comprehension of the ultimate consequences of quantum interactions is a necessary condition for the realization of what has already been coined as the Second Quantum Revolution.

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2016 GEFES prize to best theoretical thesis

QuantaLab member receives award on “Best theoretical Condensed Matter Physics PhD Thesis”


QuantaLab member José Luis Lado (INL), has received the award to the best PhD thesis of the academic year 2015-16. The prize is awarded by  the topical group on Solid State Physics  (GEFES) from  Spanish Royal Society of Physics (RSEF).  José Luis Lado made his PhD under the supervision of QuantaLab member Joaquín Fernández-Rossier (INL),   doing research on Quantum Materials, more specifically, studying “Topological electronic Phases in Graphene“.


The award ceremony will be held at the symposium on “Quantum Materials and Quantum Technologies” organized by GEFES at the next RSEF biennial meeting in July 2017.