Publications (68)
Ultimate quantum limit for amplification: a single atom in front of a mirror
Emely Wiegand, Ping-Yi Wen, Per Delsing +2
We investigate three types of amplification processes for light fields coupling to an atom near the end of a one-dimensional semi-infinite waveguide. We consider two setups where a…
Line Widths of Single-Electron Tunneling Oscillations: Experiment and Numerical Simulations
Jonas Bylander, Tim Duty, Per Delsing
We present experimental and numerical results from a real-time detection of time-correlated single-electron tunneling oscillations in a one-dimensional series array of small tunnel…
Electromagnetically induced acoustic transparency with a superconducting circuit
Gustav Andersson, Maria K. Ekström, Per Delsing
We report the observation of Electromagnetically Induced Transparency (EIT) of a mechanical field, where a superconducting artificial atom is coupled to a 1D-transmission line for…
Experimental Evaluation of Moving Target Compensation in High Time-Bandwidth Noise Radar
Martin Ankel, Robert S. Jonsson, Mats Tholen +3
In this article, the effect a moving target has on the signal-to-interference-plus-noise-ratio (SINR) for high time-bandwidth noise radars is investigated. To compensate for cell m…
Investigation of nonlinear effects in Josephson parametric oscillators used in circuit QED
Philip Krantz, Yarema Reshitnyk, Waltraut Wustmann +6
We experimentally study the behavior of a parametrically pumped nonlinear oscillator, which is based on a superconducting λ/4 resonator, and is terminated by a flux-tunable SQUID.…
Direct observation of time correlated single-electron tunneling
Jonas Bylander, Tim Duty, Per Delsing
We report a direct detection of time correlated single-electron tunneling oscillations in a series array of small tunnel junctions. Here the current, I, is made up of a lattice of…
Peripheral circuits for ideal performance of a travelling-wave parametric amplifier
Hampus Renberg Nilsson, Daryoush Shiri, Robert Rehammar +2
We investigate the required peripheral circuits to enable ideal performance for a high-gain travelling-wave parametric amplifier (TWPA) based on three-wave mixing (3WM). By embeddi…
Measurement and control of a superconducting quantum processor with a fully-integrated radio-frequency system on a chip
Mats O. Tholén, Riccardo Borgani, Giuseppe Ruggero Di Carlo +8
We describe a digital microwave platform called Presto, designed for measurement and control of multiple quantum bits (qubits) and based on the third-generation radio-frequency sys…
Microwave Quantum Optics with an Artificial Atom
Io-Chun Hoi, C. M. Wilson, Göran Johansson +4
We address the recent advances on microwave quantum optics with artificial atoms. This field relies on the fact that the coupling between a superconducting artificial atom and prop…
Fast generation of Schrödinger cat states in a Kerr-tunable superconducting resonator
X. L. He, Yong Lu, D. Q. Bao +7
Schrödinger cat states, quantum superpositions of macroscopically distinct classical states, are an important resource for quantum communication, quantum metrology and quantum com…
Squeezing and multimode entanglement of surface acoustic wave phonons
Gustav Andersson, Shan W. Jolin, Marco Scigliuzzo +6
Exploiting multiple modes in a quantum acoustic device could enable applications in quantum information in a hardware-efficient setup, including quantum simulation in a synthetic d…
Nondegenerate parametric oscillations in a tunable superconducting resonator
Andreas Bengtsson, Philip Krantz, Michaël Simoen +5
We investigate nondegenerate parametric oscillations in a multimode superconducting microwave resonator that is terminated by a SQUID. The parametric effect is achieved by modulati…
Period-tripling subharmonic oscillations in a driven superconducting resonator
Ida-Maria Svensson, Andreas Bengtsson, Philip Krantz +3
We have observed period-tripling subharmonic oscillations, in a superconducting coplanar waveguide resonator operated in the quantum regime, . The resonator is t…
Resonant and off-resonant microwave signal manipulation in coupled superconducting resonators
Mathieu Pierre, Sankar Raman Sathyamoorthy, Ida-Maria Svensson +2
We present an experimental demonstration as well as a theoretical model of an integrated circuit designed for the manipulation of a microwave field down to the single-photon level.…
Giant Cross Kerr Effect for Propagating Microwaves Induced by an Artificial Atom
Io-Chun Hoi, C. M. Wilson, Göran Johansson +4
We have investigated the cross Kerr phase shift of propagating microwave fields strongly coupled to an artificial atom. The artificial atom is a superconducting transmon qubit in a…
Quantum process tomography of continuous-variable gates using coherent states
Mikael Kervinen, Shahnawaz Ahmed, Marina Kudra +5
Encoding quantum information into superpositions of multiple Fock states of a harmonic oscillator can provide protection against errors, but it comes with the cost of requiring mor…
Transmon qubit readout fidelity at the threshold for quantum error correction without a quantum-limited amplifier
Liangyu Chen, Hang-Xi Li, Yong Lu +17
High-fidelity and rapid readout of a qubit state is key to quantum computing and communication, and it is a prerequisite for quantum error correction. We present a readout scheme f…
Quantum efficiency, purity and stability of a tunable, narrowband microwave single-photon source
Yong Lu, Andreas Bengtsson, Jonathan J. Burnett +7
We demonstrate an on-demand source of microwave single photons with 71--99\% intrinsic quantum efficiency. The source is narrowband (300\unite{kHz}) and tuneable over a 600 MHz ran…
Towards universal quantum computation through relativistic motion
David Edward Bruschi, Carlos SabÃn, Pieter Kok +3
We show how to use relativistic motion and local phase shifts to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimen…
Quantum Acoustics with Surface Acoustic Waves
Thomas Aref, Per Delsing, Maria K. Ekström +6
It has recently been demonstrated that surface acoustic waves (SAWs) can interact with superconducting qubits at the quantum level. SAW resonators in the GHz frequency range have a…
Local probing of propagating acoustic waves in a gigahertz echo chamber
Martin Gustafsson, Paulo V. Santos, Göran Johansson +1
In the same way that micro-mechanical resonators resemble guitar strings and drums, Surface Acoustic Waves (SAW) resemble the sound these instruments produce, but moving over a sol…
Three-wave mixing traveling-wave parametric amplifier with periodic variation of the circuit parameters
Anita Fadavi Roudsari, Daryoush Shiri, Hampus Renberg Nilsson +8
We report the implementation of a near-quantum-limited, traveling-wave parametric amplifier that uses three-wave mixing (3WM). To favor amplification by 3WM, we use the superconduc…
Resolving Fock states near the Kerr-free point of a superconducting resonator
Yong Lu, Marina Kudra, Timo Hillmann +4
We have designed a tunable nonlinear resonator terminated by a SNAIL (Superconducting Nonlinear Asymmetric Inductive eLement). Such a device possesses a sweet spot in which the ext…
Quantum Acoustics with Tunable Nonlinearity in the Superstrong Coupling Regime
Marco Scigliuzzo, Léo Peyruchat, Riccardo Maria Marabini +4
Precise control of mechanical modes in the quantum regime is a key resource for quantum technologies, offering promising pathways for quantum sensing with macroscopic systems and s…
Modeling and Harmonic Balance Analysis of Parametric Amplifiers for Qubit Read-out
Daryoush Shiri, Hampus Renberg Nilsson, Pavan Telluri +4
Predicting the performance of traveling-wave parametric amplifiers (TWPAs) based on nonlinear elements like superconducting Josephson junctions (JJs) is vital for qubit read-out in…
Propagating Wigner-Negative States Generated from the Steady-State Emission of a Superconducting Qubit
Yong Lu, Ingrid Strandberg, Fernando QuijandrÃa +3
We experimentally demonstrate the steady-state generation of propagating Wigner-negative states from a continuously driven superconducting qubit. We reconstruct the Wigner function…
A fast, primary Coulomb blockade thermometer
Tobias Bergsten, Tord Claeson, Per Delsing
We have measured the third derivative of the current-voltage characteristics, d^3I/dV^3, in a two-dimensional array of small tunnel junctions using a lock-in amplifier. We show tha…
Coulomb blockade thermometry using a two-dimensional array of tunnel junctions
Tobias Bergsten, Tord Claeson, Per Delsing
We have measured current-voltage characteristics of two-dimensional arrays of small tunnel junctions at temperatures from 1.5 K to 4.2 K. This corresponds to thermal energies large…
Phononic loss in superconducting resonators on piezoelectric substrates
Marco Scigliuzzo, Laure E. Bruhat, Andreas Bengtsson +3
We numerically and experimentally investigate the phononic loss for superconducting resonators fabricated on a piezoelectric substrate. With the help of finite element method simul…
Breakdown of the cross-Kerr scheme for Photon Counting
Bixuan Fan, Anton F. Kockum, Joshua Combes +6
We show, in the context of single photon detection, that an atomic three-level model for a transmon in a transmission line does not support the predictions of the nonlinear polaris…
Robust preparation of Wigner-negative states with optimized SNAP-displacement sequences
Marina Kudra, Mikael Kervinen, Ingrid Strandberg +13
Hosting non-classical states of light in three-dimensional microwave cavities has emerged as a promising paradigm for continuous-variable quantum information processing. Here we ex…
Quantized conductance and its correlation to the supercurrent in a nanowire connected to superconductors
Simon Abay, Daniel Persson, Henrik Nilsson +4
We report conductance and supercurrent of InAs nanowires coupled to Al-superconducting electrodes with short channel lengths and good Ohmic contacts. The nanowires are suspended 15…
An ultra sensitive radio frequency single electron transistor working up to 4.2 K
Henrik Brenning, Sergey Kafanov, Tim Duty +2
We present the fabrication and measurement of a radio frequency single electron transistor (rf-SET), that displays a very high charge sensitivity of 1.9 microlectrons/sqrt(Hz) at 4…
Surface acoustic wave unidirectional transducers for quantum applications
Maria K. Ekström, Thomas Aref, Johan Runeson +3
The conversion efficiency of electric microwave signals into surface acoustic waves in different types of superconducting transducers is studied with the aim of quantum application…
Current measurement by real-time counting of single electrons
Jonas Bylander, Tim Duty, Per Delsing
The fact that electrical current is carried by individual charges has been known for over 100 years, yet this discreteness has not been directly observed so far. Almost all current…
On-demand single-microwave-photon source in a superconducting circuit with wideband frequency tunability
Samarth Hawaldar, Siddhi Satish Khaire, Per Delsing +1
In this article, we propose a new method of generating single microwave photons in superconducting circuits. We theoretically show that pure single microwave photons can be generat…
Simple, robust and on-demand generation of single and correlated photons
Sankar Raman Sathyamoorthy, Andreas Bengtsson, Steven Bens +3
We propose two different setups to generate single photons on demand using an atom in front of a mirror, along with either a beam-splitter or a tunable coupling. We show that photo…
Period multiplication in a parametrically driven superconducting resonator
Ida-Maria Svensson, Andreas Bengtsson, Jonas Bylander +2
We report on the experimental observation of period multiplication in parametrically driven tunable superconducting resonators. We modulate the magnetic flux through a superconduct…
Experimental realization of deterministic and selective photon addition in a bosonic mode assisted by an ancillary qubit
Marina Kudra, Martin Jirlow, Mikael Kervinen +5
Bosonic quantum error correcting codes are primarily designed to protect against single-photon loss. To correct for this type of error, one can encode the logical qubit in code spa…
Microwave photon generation in a doubly tunable superconducting resonator
Ida-Maria Svensson, Mathieu Pierre, Michaël Simoen +7
We have developed and tested a doubly tunable resonator, with the intention to simulate fast motion of the resonator boundaries in real space. Our device is a superconducting copla…
Acoustic spectral hole-burning in a two-level system ensemble
Gustav Andersson, André Luiz Oliveira Bilobran, Marco Scigliuzzo +3
Microscopic two-level system (TLS) defects at dielectric surfaces and interfaces are among the dominant sources of loss in superconducting quantum circuits, and their properties ha…
Cavity-free vacuum-Rabi splitting in circuit quantum acoustodynamics
Andreas Ask, Maria Ekström, Per Delsing +1
Artificial atoms coupled to surface acoustic waves (SAWs) have played a crucial role in the recent development of circuit quantum acoustodynamics (cQAD). In this paper, we have inv…
Propagating phonons coupled to an artificial atom
Martin V. Gustafsson, Thomas Aref, Anton Frisk Kockum +3
Quantum information can be stored in micromechanical resonators, encoded as quanta of vibration known as phonons. The vibrational motion is then restricted to the stationary eigenm…
Single-shot Readout of a Superconducting Qubit using a Josephson Parametric Oscillator
Philip Krantz, Andreas Bengtsson, Michaël Simoen +6
We propose and demonstrate a new read-out technique for a superconducting qubit by dispersively coupling it to a Josephson parametric oscillator. We employ a tunable quarter-wavele…
Measurement of the shot noise in a single electron transistor
Sergey Kafanov, Per Delsing
We have systematically measured the shot noise in a single electron transistor (SET) as a function of bias and gate voltages. By embedding a SET in a resonance circuit we have been…
Coupling of an erbium spin ensemble to a superconducting resonator
Matthias U. Staudt, Io-Chun Hoi, Philip Krantz +9
A quantum coherent interface between optical and microwave photons can be used as a basic building block within a future quantum information network. The interface is envisioned as…
Primary thermometry of propagating microwaves in the quantum regime
Marco Scigliuzzo, Andreas Bengtsson, Jean-Claude Besse +3
The ability to control and measure the temperature of propagating microwave modes down to very low temperatures is indispensable for quantum information processing, and may open op…
Electrical post-fabrication tuning of aluminum Josephson junctions at room temperature
Christian Križan, Maurizio Toselli, Irshad Ahmad +11
Josephson junctions are key elements of superconducting quantum technology, serving as the core building blocks of superconducting qubits. We present an experimental study on room-…
Thermal properties of charge noise sources
Martin V. Gustafsson, Arsalan Pourkabirian, Göran Johansson +2
Measurements of the temperature and bias dependence of Single Electron Transistors (SETs) in a dilution refrigerator show that charge noise increases linearly with refrigerator tem…
A high gain travelling-wave parametric amplifier based on three-wave mixing
Hampus Renberg Nilsson, Anita Fadavi Roudsari, Daryoush Shiri +2
We extend the theory for a Josephson junction travelling wave parametric amplifier (TWPA) operating in the three-wave mixing regime and we propose a scheme for achieving high gain.…
Nonequilibrium heat transport and work with a single artificial atom coupled to a waveguide: emission without external driving
Yong Lu, Neill Lambert, Anton Frisk Kockum +5
We observe the continuous emission of photons into a waveguide from a superconducting qubit without the application of an external drive. To explain this observation, we build a tw…
Mitigation of interfacial dielectric loss in aluminum-on-silicon superconducting qubits
Janka Biznárová, Amr Osman, Emil Rehnman +9
We demonstrate aluminum-on-silicon planar transmon qubits with time-averaged energy relaxation times of up to , corresponding to Q = 5 million, and a highest ob…
Generation of nonclassical microwave states using an artificial atom in 1D open space
Io-Chun Hoi, Tauno Palomaki, Göran Johansson +3
We have embedded an artificial atom, a superconducting transmon qubit, in a 1D open space and investigated the scattering properties of an incident microwave coherent state. By stu…
Extensive characterization of a family of efficient three-qubit gates at the coherence limit
Christopher W. Warren, Jorge Fernández-Pendás, Shahnawaz Ahmed +13
While all quantum algorithms can be expressed in terms of single-qubit and two-qubit gates, more expressive gate sets can help reduce the algorithmic depth. This is important in th…
Decoherence benchmarking of superconducting qubits
Jonathan Burnett, Andreas Bengtsson, Marco Scigliuzzo +4
We benchmark the decoherence of superconducting qubits to examine the temporal stability of energy-relaxation and dephasing. By collecting statistics during measurements spanning m…
Improved success probability with greater circuit depth for the quantum approximate optimization algorithm
Andreas Bengtsson, Pontus Vikstål, Christopher Warren +12
Present-day, noisy, small or intermediate-scale quantum processors---although far from fault-tolerant---support the execution of heuristic quantum algorithms, which might enable a…
Nonexponential decay of a giant artificial atom
Gustav Andersson, Baladitya Suri, Lingzhen Guo +2
In quantum optics, light-matter interaction has conventionally been studied using small atoms interacting with electromagnetic fields with wavelength several orders of magnitude la…
Are pinholes the cause of excess current in superconducting tunnel junctions? A study of Andreev current in highly resistive junctions
Tine Greibe, Markku P. V. Stenberg, C. M. Wilson +3
In highly resistive superconducting tunnel junctions, excess subgap current is usually observed and is often attributed to microscopic "pinholes" in the tunnel barrier. We have stu…
Correlated frequency noise in a multimode acoustic resonator
Nuttamas Tubsrinuan, Jared H. Cole, Per Delsing +1
Frequency instabilities are a major source of errors in quantum devices. This study investigates frequency fluctuations in a surface acoustic wave (SAW) resonator, where reflection…
Charge transport in InAs nanowire Josephson junctions
Simon Abay, Daniel Persson, Henrik Nilsson +5
We present an extensive experimental and theoretical study of the proximity effect in InAs nanowires connected to superconducting electrodes. We fabricate and investigate devices w…
Characterizing decoherence rates of a superconducting qubit by direct microwave scattering
Yong Lu, Andreas Bengtsson, Jonathan J. Burnett +8
We experimentally investigate a superconducting qubit coupled to the end of an open transmission line, in a regime where the qubit decay rates to the transmission line and to its o…
Designing frequency-dependent relaxation rates and Lamb shift for a giant artificial atom
Anton Frisk Kockum, Per Delsing, Göran Johansson
In traditional quantum optics, where the interaction between atoms and light at optical frequencies is studied, the atoms can be approximated as point-like when compared to the wav…
The Single-Photon Router
Io-Chun Hoi, C. M. Wilson, Göran Johansson +3
We have embedded an artificial atom, a superconducting "transmon" qubit, in an open transmission line and investigated the strong scattering of incident microwave photons (…
Twin paradox with macroscopic clocks in superconducting circuits
Joel Lindkvist, Carlos SabÃn, Ivette Fuentes +4
We propose an implementation of a twin paradox scenario in superconducting circuits, with velocities as large as a few percent of the speed of light. Ultrafast modulation of the bo…
Universal control of a bosonic mode via drive-activated native cubic interactions
Axel M. Eriksson, Théo Sépulcre, Mikael Kervinen +9
Linear bosonic modes offer a hardware-efficient alternative for quantum information processing but require access to some nonlinearity for universal control. The lack of nonlineari…
Storage and on-demand release of microwaves using superconducting resonators with tunable coupling
Mathieu Pierre, Ida-Maria Svensson, Sankar Raman Sathyamoorthy +2
We present a system which allows to tune the coupling between a superconducting resonator and a transmission line. This storage resonator is addressed through a second, coupling re…
Extensible quantum simulation architecture based on atom-photon bound states in an array of high-impedance resonators
Marco Scigliuzzo, Giuseppe Calajò, Francesco Ciccarello +7
Engineering the electromagnetic environment of a quantum emitter gives rise to a plethora of exotic light-matter interactions. In particular, photonic lattices can seed long-lived…
A small footprint travelling-wave parametric amplifier with a high Signal-to-Noise Ratio improvement in a wide band
Hampus Renberg Nilsson, Liangyu Chen, Giovanna Tancredi +6
We characterise a small footprint travelling-wave parametric amplifier (TWPA). The TWPA is built with magnetically flux-tunable superconducting nonlinear asymmetric inductive eleme…