From 10th to 14th June 2024 the second conference devoted to first-principles calculations of defect qubits’ magneto-optical and spin properties for defect technologies was held at the Eötvös University in Budapest, Hungary where theory also met experiments to discuss scientific issues.

This conference welcomed 154 participants from 28 countries registered for the workshop from 5 continents including the organizers. The participants showed up in person at the workshop site and attended the scientific talks except for one attendee with on-line participation. The final scientific program of the workshop lasted for five full days, included 18 invited talks, 41 contributing talks, and a poster session with 87 posters, and a Discussion session about single defect engineering with leading experimentalists and theorist. The event was sponsored jointly by the Psi-k organization, CECAM HQ, Eötvös Loránd University (Budapest, Hungary), Quantum Information National Laboratory of Hungary, and the Applied Physics Letters.

The purpose of this conference to bring together world-leading theoreticians and experimentalists active in the field of quantum information processing based on solid state qubits. Our discussions improve interdisciplinary cooperation overcoming traditional boundaries between scientific disciplines. Invited speakers at DSQT2024 workshop represented electronic structure theory community, theory at phenomenological and atomic scale level, materials growth, defect engineering, surface chemistry, quantum optics and spin physics. Recognized leaders in the field, highlighted recent progress and discuss challenges and opportunities in their invited talks. Invited talks, contributed talks, posters, and the Discussion session stimulated the exchange of methodological expertise and new developments between scientists working on different aspects of the field, illuminate opportunities for optimizing the materials properties and device design aided by theory.

The conference was originally designed to host 100 participants, but given the unexpectedly high level of requests for participation an effort was made to increase numbers and accommodate 150+ participants.

Detailed Program

Monday June 10th 2024 – Day 1

• 08:00 to 09:20 – Registration

• 09:20 to 10:00 – Registration + Introduction

Theory for scaling up: searching and characterization

• 10:00 to 10:40 – Volker Blum – Dopants and compensating defects in hybrid perovskites from hybrid DFT – in supercell models with thousands of atoms

• 10:40 to 11:00 – Coffee break

Theory: screening and excited states

• 11:00 to 11:20 – Joel Davidsson – Exploration of the ADAQ Defect Database for Quantum Applications

• 11:20 to 11:40 – Ji Chen – Correlated electronic structure of defects in solids from quantum Monte Carlo calculations.

• 11:40 to 12:00 – Zsolt Benedek – Advancing quantum defect characterization in semiconductors: a comprehensive ab initio multireference study of the NV center in diamond

• 12:00 to 13:40 – Lunch

Color center in 2D materials

• 13:40 to 14:20 – Hannah L. Stern – A quantum coherent spin in a two-dimensional material at room temperature

• 14:20 to 15:00 – Burcu Ozden – Harnessing Proton Irradiation for Precision Defect Engineering in 2D Materials

• 15:00 to 15:20 – Coffee break

Diamond NV: novel control schemes

• 15:20 to 15:40 – Ronald Ulbricht – New insights into the electronic structure of nitrogen-vacancy centers in diamond

• 15:40 to 16:00 – Ferenc Simon – Spectroscopy and terahertz maser effect in diamond with ultra‐dense NV concentration

• 16:00 to 16:20 – Hosung Seo – The impact of paramagnetic defects on the decoherence dynamics of nitrogen-vacancy center in diamond

• 16:20 to 16:40 – Eisuke Abe – Suppression of Pulsed Dynamic Nuclear Polarization by Many-Body Spin Dynamics

• 16:40 to 18:40 – Welcome reception

Tuesday June 11th 2024 – Day 2

Silicon carbide qubits I

• 09:00 to 09:40 – Cristian Bonato – Telecom O-band single vanadium spin defects in SiC with ultra-narrow inhomogeneous broadening

• 09:40 to 10:20 – Jörg Wrachtrup – TBA

• 10:20 to 10:40 – Son NGUYEN – Identification of Negatively Charged Tungsten in 4H-SiC

• 10:40 to 11:00 – Coffee break

Silicon carbide qubits II

• 11:00 to 11:20 – Benedikt Tissot – Strain Engineering for Transition Metal Defects in SiC

• 11:20 to 11:40 – Marianne Bathen – Selective formation of vacancy-related emitters in SiC

• 11:40 to 12:00 – Ji-Yang Zhou – Plasmonic-Enhanced Bright Single Spin Defects in Silicon Carbide Membranes

• 12:00 to 13:40 – Lunch

Diamond NV center: electrical control

• 13:40 to 14:20 – Michael Trupke – Quantum sensing with electrical readout of nitrogen-vacancy centres in diamond

• 14:20 to 14:40 – Juanita Bocquel – Temperature and Electric Field Dependent Photophysics of Single Nitrogen-Vacancy Centers in Diamond

• 14:40 to 15:00 – Michael Petrov – On the origin of the photovoltaic effect of an NV center

• 15:00 to 15:20 – Coffee break

Diamond NV center for quantum sensing

• 15:20 to 15:40 – Hao-Cheng Weng – Crosstalk-mitigated microelectronic control for optically-active spins

• 15:40 to 16:00 – Rémi Blinder – Prospects for hyperpolarization at room temperature with nanodiamonds

• 16:00 to 16:20 – Fabian Freire-Moschovitis – The role of electrolytes in the relaxation of near-surface spin defects in diamond

• 16:20 to 16:40 – Madhav Gupta – Widefield Diamond Quantum Sensing with Neuromorphic Vision Sensors

• 16:40 to 18:40 – Poster session: SiC, diamond NV quantum simulation and computing, diamond alternative color center formation, Si and alternative 3D materials

Wednesday June 12th 2024 – Day 3

Theory of excited states in periodic models I

• 09:00 to 09:40 – Marco Govoni – Excited State Properties of Point Defects in Semiconductors and Insulators Investigated with Time-Dependent Density Functional Theory and Quantum Embedding Methods

• 09:40 to 10:20 – Cyrus E. Dreyer – Embedding methods for quantum defects

• 10:20 to 10:40 – Michel Bockstedte – Understanding the spin-selective transitions of color center for quantum applications by ab initio theory

• 10:40 to 11:00 – Coffee break

Color centers in silicon

• 11:00 to 11:40 – Anaïs Dréau – Rotation of the center-of-mass of single G centers in silicon-on-insulator

• 11:40 to 12:00 – Aaron Day – Electrical Manipulation of Telecom Color Centers in Silicon

• 12:00 to 13:40 – Lunch

Diamond NV center: quantum simulation and sensing

• 13:40 to 14:20 – Fedor Jelezko – Quantum simulation in isotopically engineered diamond

• 14:20 to 15:00 – Aparatija Singha – Quantum sensing with single spin sensitivity

• 15:00 to 15:20 – Coffee break

Color centers in diamond I

• 15:20 to 15:40 – Gergo Thiering – Ab-initio theory of nuclear spin flip processes within NV and G4V centers in diamond via orbital degrees of freedom

• 15:40 to 16:00 – Lukas Razinkovas – Optical spectra of Jahn-Teller active color centers: A theoretical approach

• 16:00 to 16:20 – Margriet van Riggelen – High-fidelity gates in a multi-qubit diamond quantum processor

• 16:20 to 16:40 – Philipp Vetter – Discrete time-crystalline order in a deterministically grown, sub-1 nm nuclear spin layer in diamond

• 16:40 to 18:40 – Discussion section

• 19:00 to 22:30 – Cruising and dinner on Danube

Thursday June 13th 2024 – Day 4

Rare-earth ions and color centers in Si

• 09:00 to 09:40 – Patrice Bertet – Detection and spectroscopy of individual Er3+ spins in CaWO4 using microwave photon counting

• 09:40 to 10:20 – Andreas Reiserer – Erbium dopants for quantum networks

• 10:20 to 10:40 – Greta Andrini – Nanosecond laser-induced activation of telecom quantum emitters in ion implanted silicon

• 10:40 to 11:00 – Coffee break

Search for qubits in 3D and 2D materials

• 11:00 to 11:40 – Kristian Thygesen – High-throughput discovery of quantum defects in low dimensional crystals

• 11:40 to 12:00 – Louis Alaerts – Stark shift on the negatively charged nitrogen-vacancy center in diamond

• 12:00 to 13:40 – Lunch

Theory of 2D materials

• 13:40 to 14:20 – Anton Pershin – Environmental Control of Single Photon Emission in hBN

• 14:20 to 15:00 – Sivan Refaely-Abramson – Excited-State Phenomena at Defects in 2D Semiconductors: a Many-Body Perspective

• 15:00 to 15:20 – Coffee break

Silicon carbide qubits III

• 15:20 to 15:40 – Vadim Vorobyov – Characterisation of nuclear spin networks in 4H silicon carbide

• 15:40 to 16:00 – Samuel White – Dephasing Times and Magnetic Field Sensitivity of the Silicon Vacancy in Isotopically-Purified 4H-SiC

• 16:00 to 16:20 – Dominic Catanzaro – Integrated Control of Silicon Carbide Quantum Photonics

• 16:20 to 16:40 – Laurens Feije – Spectral diffusion dynamics of narrow-linewidth emitters in commercially available bulk 4H-silicon carbide

• 16:40 to 18:40 – Poster session: Theoretical methods, diamond NV sensing, alternative diamond color centers, 2D materials

Friday June 14th 2024 – Day 5

Theory of excited states in periodic models II

• 09:00 to 09:40 – Vsevolod Ivanov – Understanding control and modulation of color center defects

• 09:40 to 10:20 – David Strubbe – Ground and excited states of open-shell quantum defects from the spin-flip Bethe-Salpeter approach

• 10:20 to 10:40 – Jonah Nagura – Spin noise at diamond surfaces from first principles

• 10:40 to 11:00 – Coffee break

Color centers in diamond II

• 11:00 to 11:20 – Sébastien Pezzagna – Polymorphs of the 17O-implanted ST1 spin centre in diamond and spectroscopy of the hyperfine interaction to nuclear spins

• 11:20 to 11:40 – Andrea Corazza – Single Neutral Silicon Vacancy centers in thin hydrogen-terminated diamond membranes

• 11:40 to 12:00 – Katharina Senkalla – Germanium-Vacancy in Diamond as Quantum Memory exceeding 20ms

• 12:00 to 13:40 – Lunch

Color centers in hexagonal boron nitride I

• 13:40 to 14:00 – Nai-Jie Guo – Coherent control of an ultrabright single spin in hexagonal boron nitride at room temperature

• 14:00 to 14:20 – Joachim Leibold – Extending the room temperature spin coherence time of boron vacancies in hexagonal boron nitride for quantum sensing

• 14:20 to 14:40 – Marek Maciaszek – Blue quantum emitter (435 nm) in hexagonal boron nitride – proposition of identification

• 14:40 to 15:00 – Ádám Ganyecz – First principles theory of the nitrogen interstitial in hBN: a plausible model for the blue emitter

• 15:00 to 15:20 – Coffee break

Color centers in hexagonal boron nitride II

• 15:20 to 15:40 – Piotr Tatarczak – Single-photon emission from hBN activated by deterministic bubble formation

• 15:40 to 16:00 – Rohit Babar – Carbon-contaminated grain boundaries and Stone-Wales defects in hBN as potential single photon emitters

• 16:00 to 16:20 – Song Li – Quantum Emission from Donor-Acceptor Pairs in hBN

• 16:20 to 16:40 – Closing Word

 

Invited speakers

THEORY

Denmark

Kristian Sommer Thygesen (DTU)

Hungary

Anton Pershin (Wigner Research Centre for Physics)

Israel

Sivan Refaely-Abramson (Weizmann Institute of Science)

Italy

Marco Govoni (University of Modena and Reggio Emilia)

Sweden
Oscar Bulancea-Lindvall (Linköping University)

USA

Volker Blum (Duke University)

Liang Tan (LBNL)

David Strubbe (University of California, Merced)

Cyrus E. Dreyer (Stony Brook University)

 

EXPERIMENT

Austria

Michael Trupke (Austrian Academy of Sciences)

France

Patrice Bertet (University of Paris-Saclay)

Anaïs Dréau (Université de Montpellier)

Germany

Jörg Wrachtrup (University of Stuttgart)

Fedor Jelezko (University of Ulm)

Andreas Reiserer (Technische Universität München)

Aparatija Singha (Max Planck Institute, Stuttgart)

United Kingdom

Hannah L. Stern (Cambridge University)

Cristian Bonato (Heriot-Watt University)

USA

Burcu Ozden (Penn State Abington)

 

Organizers

The organizers of the conference were:

• Adam Gali (HUN-REN Wigner Research Centre for Physics/Budapest University of Technology and Economics)
• Viktor Ivády (Eötvös Loránd University)
• Igor Abrikosov (Linkoping University)
• Nathalie P. De Leon (Princeton University)
• Yuan Ping (University of Wisconsin-Madison)

 

General remarks and feedback from participants

We found sponsors to finance the “Best poster award” that were given to a youth male scientist and a female scientist to maximize the inclusivity in both career stage and gender. We believe that we could indeed inspire the young generation of scientists by the award. Furthermore, contributed talks from early career stage scientists were given and we had a very positive feedback from these scientists in social media after the conference (e.g., LinkedIn posts). We had 5 female invited speakers to encourage youth female scientists of the audience in their career. Although, the workshop was planned exclusively in person but we offered to one female invited scientist to present her results on-line because of the difficulties to travel with her recently born baby. In the organization and local organization teams we have women and men with diverse cultural background to run the conference in order to secure an inclusive environment for people with any gender or geographical locations of various habits.

Conclusions and prospects

This conference was very successful on all fronts: the number of applicants exceeded our expectations, all lecturers did a wonderful job in preparing and delivering carefully-prepared lectures, and participants responded very positively and contributed with their energy and enthusiasm to make the best of this conference. Discussions amongst the attendees of the conferences highlighted the interest in not only continuing DSQT in its current form but also the idea of holding more specific workshops that focus on different topics within the area of ‘defects for quantum technology’. One idea that was discussed is a meeting focused on defects in two-dimensional materials, or a meeting that would include the community of those working on molecular spins for quantum technology. This could include not only the traditional electron paramagnetic resonance community interested in inorganic high spin complexes, but also the organic molecular community where the photophysics of optically addressable spins resembles that of defects in wide bandgap solids. By combining the two fields (molecular spins and solid-state defects) we would hope to broaden the theoretical and experimental approach to studying these systems. Separately, grant proposals and collaborations were discussed by participants at the meeting forming European/UK consortia.

This event would not have been possible without the impeccable local organization team from ELTE and generous support of Eötvös Loránd University (ELTE). In particular, Viktor Ivády’s team provided a great service to run the conference smoothly.

Given the very enthusiastic response of participants and lecturers alike, it will make sense to reiterate this event biannually to advance this rapidly evolving field.

 

Further details

Event website, with program, list of participants and abstracts