67 citations · 441 across the 23 of their papers we have counts for
23 papers
Efficient electronic cooling above 2 K by niobium-based superconducting tunnel junctions
J. Hätinen, A. Ronzani, R. P. Loreto +15
Replacing the bulky cryoliquid-based cooling stages of cryoenabled instruments by chip-scale refrigeration is envisioned to disruptively reduce the system size similar to microproc…
Effect of ion irradiation on superconducting thin films
Katja Kohopää, Alberto Ronzani, Robab Najafi Jabdaraghi +8
We demonstrate ion irradiation by argon or gallium as a wafer-scale post-processing method to increase disorder in superconducting thin films. We study several widely used supercon…
Thermal resistance in superconducting flip-chip assemblies
Joel Hätinen, Emma Mykkänen, Klaara Viisanen +5
Cryogenic microsystems that utilize different 3D integration techniques are being actively developed, e.g., for the needs of quantum technologies. 3D integration can introduce oppo…
Phonon-blocked junction refrigerators for cryogenic quantum devices
E. Mykkänen, J. S. Lehtinen, A. Ronzani +4
Refrigeration is an important enabler for quantum technology. The very low energy of the fundamental excitations typically utilized in quantum technology devices and systems requir…
Scalable on-chip multiplexing of silicon single and double quantum dots
Heorhii Bohuslavskyi, Alberto Ronzani, Joel Hätinen +5
Owing to the maturity of complementary metal oxide semiconductor (CMOS) microelectronics, qubits realized with spins in silicon quantum dots (QDs) are considered among the most pro…
Supporting quantum technologies with an ultra-low loss silicon photonics platform
Matteo Cherchi, Arijit Bera, Antti Kemppinen +9
Photonic integrated circuits (PICs) are expected to play a significant role in the ongoing second quantum revolution, thanks to their stability and scalability. Still, major upgrad…
Superconducting insulators and localization of Cooper pairs
Konstantin Yu. Arutyunov, Janne S. Lehtinen, Alexey Radkevich +2
Rapid miniaturization of electronic devices and circuits demands profound understanding of fluctuation phenomena at the nanoscale. Superconducting nanowires -- serving as important…
Coulomb Blockade Thermometry on a Wide Temperature Range
O. M. Hahtela, A. Kemppinen, J. Lehtinen +11
The Coulomb Blockade Thermometer (CBT) is a primary thermometer for cryogenic temperatures, with demonstrated operation from below 1 mK up to 60 K. Its performance as a primary the…
Dispersive readout of reconfigurable ambipolar quantum dots in a silicon-on-insulator nanowire
Jingyu Duan, Janne S. Lehtinen, Michael A. Fogarty +8
We report on ambipolar gate-defined quantum dots in silicon on insulator (SOI) nanowires fabricated using a customised complementary metal-oxide-semiconductor (CMOS) process. The a…
Cascaded superconducting junction refrigerators: optimization and performance limits
A. Kemppinen, A. Ronzani, E. Mykkänen +3
We demonstrate highly transparent silicon-vanadium and silicon-aluminum tunnel junctions with relatively low sub-gap leakage current and discuss how a trade-off typically encounter…
Nanobolometer with Ultralow Noise Equivalent Power
R. Kokkoniemi, J. Govenius, V. Vesterinen +10
Since the introduction of bolometers more than a century ago, they have been applied in a broad spectrum of contexts ranging from security and the construction industry to particle…
Flux-driven Josephson parametric amplifier for sub-GHz frequencies fabricated with side-wall passivated spacer junction technology
Slawomir Simbierowicz, Visa Vesterinen, Leif Grönberg +3
We present experimental results on a Josephson parametric amplifier tailored for readout of ultra-sensitive thermal microwave detectors. In particular, we discuss the impact of fab…
Superconducting MoSi nanowires
J. S. Lehtinen, A. Kemppinen, E. Mykkänen +2
We have fabricated disordered superconducting nanowires of molybdenium silicide. A molybdenium nanowire is first deposited on top of silicon, and the alloy is formed by rapid therm…
Side-wall spacer passivated sub-um Josephson junction fabrication process
Leif Grönberg, Mikko Kiviranta, Visa Vesterinen +5
We present a structure and a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography. The key element is a side-wall-pa…
Characterising superconducting filters using residual microwave background
J. S. Lehtinen, E. Mykkänen, A. Kemppinen +3
A normal metal - superconductor hybrid single-electron trap with tunable barrier is utilized as a tool for spectrum analysis at the extremely low signal levels, using only well fil…
Reducing current noise in cryogenic experiments by vacuum-insulated cables
E. Mykkänen, J. S. Lehtinen, A. Kemppinen +4
We measure the current noise of several cryogenic cables in a pulse tube based dilution refrigerator at frequencies between about 1~mHz and 50~kHz. We show that vibration-induced n…
The quantum phase slip phenomenon in superconducting nanowires with high-impedance environment
K. Yu. Arutyunov, J. S. Lehtinen, T. Rantala
Quantum phase slip (QPS) is the particular manifestation of quantum fluctuations of the order parameter of a current-biased quasi-1D superconductor. The QPS event(s) can be conside…
Junctionless Cooper pair transistor
K. Yu. Arutyunov, J. S. Lehtinen
Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous…
Insulating State of a Quasi-1-Dimensional Superconductor
J. S. Lehtinen, T. Rantala, K. Yu. Arutyunov
The topic of quantum fluctuations in quasi-1D superconductors, also called quantum phase slips (QPS), has attracted a significant attention. It has been shown that the phenomenon i…
Coulomb blockade and Bloch oscillations in superconducting Ti nanowires
J. S. Lehtinen, K. Zakharov, K. Yu. Arutyunov
Quantum fluctuations in quasi-one-dimensional superconducting channels leading to spontaneous changes of the phase of the order parameter by , alternatively called quantum phas…
Quantum phase slip phenomenon in superconducting nanowires with low-Ohmic environment
Janne Lehtinen, Konstantin Arutyunov
In a number of recent experiments it has been demonstrated that in ultra-narrow superconducting channels quantum fluctuations of the order parameter, alternatively called quantum p…
Quantum phase slip phenomenon in ultra-narrow superconducting nanorings
K. Yu. Arutyunov, T. T. Hongisto, J. S. Lehtinen +2
The smaller the system, typically - the higher is the impact of fluctuations. In narrow superconducting wires sufficiently close to the critical temperature Tc thermal fluctuations…
Evidence of quantum phase slip effect in titanium nanowires
Janne Lehtinen, Timo Sajavaara, Konstantin Arutyunov +1
Electron transport properties of titanium nanowires were experimentally studied. Below the effective diameter 50 nm all samples demonstrated a pronounced broadening of t…