Department of Applied Physics

Superconducting Qubits and Circuit QED (KVANTTI)

Out group is doing research in fields of quantum information and quantum-level effects in superconducting devices, quantum coherent matter, and interaction of electromagnetic fields with nano-structured materials.
Artistic impression of the sample, the pulse sequence, and the density matrix. Image by Antti Paraoanu.

We are a part of the effort in nanoelectronics in the Low Temperature Laboratory, Department of Applied Physics


Group leader

Dr. Sorin Paraoanu

Research

Superconducting qubits and circuit QED

Our group focuses on the study of quantum effects in superconducting circuits comprising qubits and resonators. This is a remarkably versatile experimental platform, allowing us to dive into fundamental physical phenomena and, in the long term, aiming at applications such as quantum computers and simulators.

Some of our topics of interest:

  • Quantum state control of superconducting qubits using microwave pulses. See the trajectories on the Bloch sphere shown above; a movie is available here<https://ltl.tkk.fi/wiki/images/0/02/Trajectories.ogv>
  • Entanglement and dissipation
  • Frequency modulation effects with superconducting qubits
  • Parametric modulation of superconducting circuits and the dynamical Casimir effect
  • Architectures for quantum computing and quantum simulation

Microwave photonics

The high-frequency measurement techniques for the work on superconducting circuits can be employed in other contexts as well. Novel materials have recently been fabricated using nanotechnology. Our goal is to understand how these new types of materials, placed in cavities or in transmission lines, interact with microwave fields.

Some of our topics of interest:

  • Novel methods for extracting the microwave permittivity and permeability using coaxial air lines
  • Carbon nanotubes in electromagnetic cavities

Quantum coherent matter

We are interested in phenomena related to tunnelling in Bose-Einstein condensates, and the properties of the phase of the order parameter. We have been investigating many-body fragmented states realized with bosonic atoms in double-well traps as well as Josephson effects in fermionic gases.

Facilities

The Kvantti group is part of the Low Temperature Laboratory in the Department of Applied Physics. We are located in Nanotalo. We have immediate access to the nanofabrication equipment in the clean rooms of Micronova and the national research infrastructure OtaNano, including the Low Temperature Laboratory and imaging facilities in the Nanomicroscopy Center.

GMW 5403 room-temperature electromagnet

For measurements at room temperature in a magnetic field, we employ a GMW 76mm electromagnet model 5403 with a Sorensen DKM40-75E power supply. This device is used for testing various samples in magnetic fields and for the characterization of nanomagnetic composites in the microwave range.

  • Specifications: pole gap = 0-86 mm; pole diameter = 76 mm; maximum field = 1.5 T; power supply current = 0-75 A; power supply voltage = 0-40 V.
Image: Unto Rautio

Low Temperature Laboratory

The Low Temperature Laboratory at Aalto University is one of the world centres in ultra-low temperature physics and technology. The leading position is based on vigorous in-house development and construction of sub-mK refrigerators.

OtaNano

Latest publications

Detecting virtual photons in ultrastrongly coupled superconducting quantum circuits

L. Giannelli, E. Paladino, M. Grajcar, G. S. Paraoanu, G. Falci 2024 PHYSICAL REVIEW RESEARCH

Critical parametric quantum sensing

R. Di Candia, F. Minganti, K.V. Petrovnin, G.S. Paraoanu, S. Felicetti 2023 npj Quantum Information

Integrated conversion and photodetection of virtual photons in an ultrastrongly coupled superconducting quantum circuit

Luigi Giannelli, Giorgio Anfuso, Miroslav Grajcar, Gheorghe Sorin Paraoanu, Elisabetta Paladino, Giuseppe Falci 2023 EUROPEAN PHYSICAL JOURNAL: SPECIAL TOPICS

Optimized emulation of quantum magnetometry via superconducting qubits

N. N. Gusarov, M. R. Perelshtein, P. J. Hakonen, G. S. Paraoanu 2023 Physical Review A

Reflection-enhanced gain in traveling-wave parametric amplifiers

S. Kern, P. Neilinger, E. Il'Ichev, A. Sultanov, M. Schmelz, S. Linzen, J. Kunert, G. Oelsner, R. Stolz, A. Danilov, S. Mahashabde, A. Jayaraman, V. Antonov, S. Kubatkin, M. Grajcar 2023 Physical Review B

Microwave Gaussian quantum sensing with a CNOT gate receiver

Hany Khalifa, Kirill Petrovnin, Riku Jantti, Gheorghe Sorin Paraoanu 2023 IEEE Access

Theory of coherent interaction-free detection of pulses

John J. McCord, Shruti Dogra, Gheorghe Sorin Paraoanu 2023 PHYSICAL REVIEW RESEARCH

Generation and Structuring of Multipartite Entanglement in a Josephson Parametric System

Kirill Viktorovich Petrovnin, Michael Romanovich Perelshtein, Tero Korkalainen, Visa Vesterinen, Ilari Lilja, Gheorghe Sorin Paraoanu, Pertti Juhani Hakonen 2023 Advanced Quantum Technologies

Coherent interaction-free detection of microwave pulses with a superconducting circuit

Shruti Dogra, John J. McCord, Gheorghe Sorin Paraoanu 2022 Nature Communications

Experimental demonstration of robustness under scaling errors for superadiabatic population transfer in a superconducting circuit

Shruti Dogra, Antti Vepsäläinen, Gheorghe Sorin Paraoanu 2022 Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
More information on our research in the Aalto research portal.
Research portal
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