101 citations · 629 across the 22 of their papers we have counts for
22 papers
Methods to achieve near-millisecond energy relaxation and dephasing times for a superconducting transmon qubit
Mikko Tuokkola, Yoshiki Sunada, Heidi Kivijärvi +6
Superconducting qubits are one of the most promising physical systems for implementing quantum computers. However, executing quantum algorithms of practical computational advantage…
Signal crosstalk in a flip-chip quantum processor
Sandoko Kosen, Hang-Xi Li, Marcus Rommel +15
Quantum processors require a signal-delivery architecture with high addressability (low crosstalk) to ensure high performance already at the scale of dozens of qubits. Signal cross…
Experimentally verified, fast analytic and numerical design of superconducting resonators in flip-chip architectures
Hang-Xi Li, Daryoush Shiri, Sandoko Kosen +10
In superconducting quantum processors, the predictability of device parameters is of increasing importance as many labs scale up their systems to larger sizes in a 3D-integrated ar…
Initial experimental results on a superconducting-qubit reset based on photon-assisted quasiparticle tunneling
V. A. Sevriuk, W. Liu, J. Rönkkö +15
We present here our recent results on qubit reset scheme based on a quantum-circuit refrigerator (QCR). In particular, we use the photon-assisted quasiparticle tunneling through a…
Qubit-compatible substrates with superconducting through-silicon vias
K. Grigoras, N. Yurttagül, J. -P. Kaikkonen +21
We fabricate and characterize superconducting through-silicon vias and electrodes suitable for superconducting quantum processors. We measure internal quality factors of a million…
A low-noise on-chip coherent microwave source
Chengyu Yan, Juha Hassel, Visa Vesterinen +5
The scaleup of quantum computers operating in the microwave domain requires advanced control electronics, and the use of integrated components that operate at the temperature of th…
Two-stage SQUID amplifier with bias current re-use
Mikko Kiviranta
We have designed and fabricated an integrated two-stage SQUID amplifier, requiring only one bias line and one flux setpoint line. From the biasing viewpoint the two stages are conn…
Characterizing cryogenic amplifiers with a matched temperature-variable noise source
Slawomir Simbierowicz, Visa Vesterinen, Joshua Milem +7
We present a cryogenic microwave noise source with a characteristic impedance of 50 , which can be installed in a coaxial line of a cryostat. The bath temperature of the noise s…
Photon-number-dependent effective Lamb shift
Arto Viitanen, Matti Silveri, Máté Jenei +8
The Lamb shift, an energy shift arising from the presence of the electromagnetic vacuum, has been observed in various quantum systems and established as the part of the energy shif…
Broadband Tunable Phase Shifter For Microwaves
Jinli Zhang, Tianyi Li, Roope Kokkoniemi +8
We implement a broadly tunable phase shifter for microwaves based on superconducting quantum interference devices (SQUIDs) and study it both experimentally and theoretically. At di…
Calibration of cryogenic amplification chains using normal-metal--insulator--superconductor junctions
Eric Hyyppä, Máté Jenei, Shumpei Masuda +7
Various applications of quantum devices call for an accurate calibration of cryogenic amplification chains. To this end, we present a convenient calibration scheme and use it to ac…
Optimized heat transfer at exceptional points in quantum circuits
Matti Partanen, Jan Goetz, Kuan Yen Tan +12
Superconducting quantum circuits are potential candidates to realize a large-scale quantum computer. The envisioned large density of integrated components, however, requires a prop…
Qubit Measurement by Multichannel Driving
Joni Ikonen, Jan Goetz, Jesper Ilves +10
We theoretically propose and experimentally implement a method of measuring a qubit by driving it close to the frequency of a dispersively coupled bosonic mode. The separation of t…
Multiplexed readout of kinetic inductance bolometer arrays
Hannu Sipola, Juho Luomahaara, Andrey Timofeev +4
Kinetic inductance bolometer (KIB) technology is a candidate for passive sub-millimeter wave and terahertz imaging systems. Its benefits include scalability into large 2D arrays an…
Observation of a broadband Lamb shift in an engineered quantum system
Matti Silveri, Shumpei Masuda, Vasilii Sevriuk +9
The shift of energy levels owing to broadband electromagnetic vacuum fluctuations, the Lamb shift, has been pivotal in the development of quantum electrodynamics and in understandi…
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…
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…
Conformal Titanium Nitride in a Porous Silicon Matrix: a Nanomaterial for In-Chip Supercapacitors
Kestutis Grigoras, Jari Keskinen, Leif Grönberg +6
Today's supercapacitor energy storages are typically discrete devices aimed for printed boards and power applications. The development of autonomous sensor networks and wearable el…
Kinetic Inductance Magnetometer
Juho Luomahaara, Visa Vesterinen, Leif Grönberg +1
Ultrasensitive magnetic field detection is utilized in the fields of science, medicine and industry. We report on a novel magnetometer relying on the kinetic inductance of supercon…
Verification of stable operation of rapid single flux quantum devices with selective dissipation
J. Hassel, L. Gronberg, P. Helisto
It has been suggested that Rapid Single Flux Quantum (RSFQ) devices could be used as the classical interface of superconducting qubit systems. One problem is that the interface act…
Characterization of a fabrication process for the integration of superconducting qubits and RSFQ circuits
Maria Gabriella Castellano, Leif Gronberg, Pasquale Carelli +7
In order to integrate superconducting qubits with rapid-single-flux-quantum (RSFQ) control circuitry, it is necessary to develop a fabrication process that fulfills at the same tim…