335 citations · 1.1k across the 25 of their papers we have counts for
27 papers
Optimal robust single-qubit gates in superconducting quantum processors
Tangyou Huang, Anuj Aggarwal, Jingjun Zhu +11
Fault-tolerant quantum computing requires high-fidelity quantum gates that are resilient to control errors and device imperfections. Here, we develop energy-optimal control pulses…
Demonstrating and Benchmarking Classical Shadows for Lindblad Tomography
Rune Thinggaard Birke, Johann Bock Severin, Malthe A. Marciniak +15
Spurious couplings and decoherence degrade the performance of solid-state quantum processors, demanding careful design, calibration, and mitigation protocols. These strategies ofte…
Real-time adaptive tracking of fluctuating relaxation rates in superconducting qubits
Fabrizio Berritta, Jacob Benestad, Jan A. Krzywda +17
The fidelity of operations on a solid-state quantum processor is fundamentally bounded by environmental decoherence. Characterizing environmental fluctuations is challenging becaus…
Neural-network-based design and implementation of fast and robust quantum gates
Marko Kuzmanović, Ilya Moskalenko, Yu-Han Chang +11
We present a continuous-time, neural-network-based approach to optimal control in quantum systems, with a focus on pulse engineering for quantum gates. Leveraging the framework of…
Quantum Process Tomography with Digital Twins of Error Matrices
Tangyou Huang, Akshay Gaikwad, Ilya Moskalenko +19
Accurate and robust quantum process tomography (QPT) is crucial for verifying quantum gates and diagnosing implementation faults in experiments aimed at building universal quantum…
Mitigating transients in flux-control signals in a superconducting quantum processor
Anuj Aggarwal, Jorge Fernández-Pendás, Tahereh Abad +12
Flux-tunable qubits and couplers are common components in superconducting quantum processors. However, dynamically controlling these elements via current pulses poses challenges du…
Quantum SWAP gate realized with CZ and iSWAP gates in a superconducting architecture
Christian Križan, Janka Biznárová, Liangyu Chen +19
It is advantageous for any quantum processor to support different classes of two-qubit quantum logic gates when compiling quantum circuits, a property that is typically not seen wi…
Fast unconditional reset and leakage reduction in fixed-frequency transmon qubits
Liangyu Chen, Simon Pettersson Fors, Zixian Yan +24
The realization of fault-tolerant quantum computing requires the execution of quantum error-correction (QEC) schemes, to mitigate the fragile nature of qubits. In this context, to…
Quantum synchronization in one-dimensional topological systems
Tong Liu, Laura García-Álvarez, Giovanna Tancredi
The phenomenon of synchronization, where entities exhibit stable oscillations with aligned frequencies and phases, has been detected in diverse areas of natural science. It plays a…
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…
Dispersive Qubit Readout with Intrinsic Resonator Reset
M. Jerger, F. Motzoi, Y. Gao +9
A key challenge in quantum computing is speeding up measurement and initialization. Here, we experimentally demonstrate a dispersive measurement method for superconducting qubits t…
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…
Mitigation of frequency collisions in superconducting quantum processors
Amr Osman, Jorge Fernàndez-Pendàs, Christopher Warren +6
The reproducibility of qubit parameters is a challenge for scaling up superconducting quantum processors. Signal crosstalk imposes constraints on the frequency separation between n…
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…
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…
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…
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…
Reference-State Error Mitigation: A Strategy for High Accuracy Quantum Computation of Chemistry
Phalgun Lolur, Mårten Skogh, Christopher Warren +6
Decoherence and gate errors severely limit the capabilities of state-of-the-art quantum computers. This work introduces a strategy for reference-state error mitigation (REM) of qua…
Building Blocks of a Flip-Chip Integrated Superconducting Quantum Processor
Sandoko Kosen, Hang-Xi Li, Marcus Rommel +24
We have integrated single and coupled superconducting transmon qubits into flip-chip modules. Each module consists of two chips -- one quantum chip and one control chip -- that are…
Fast multi-qubit gates through simultaneous two-qubit gates
Xiu Gu, Jorge Fernández-Pendás, Pontus Vikstål +8
Near-term quantum computers are limited by the decoherence of qubits to only being able to run low-depth quantum circuits with acceptable fidelity. This severely restricts what qua…
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…
Critical slowing down in the bistable regime of circuit quantum electrodynamics
P. Brookes, G. Tancredi, A. D. Patterson +5
We investigate the dynamics of the bistable regime of the generalized Jaynes-Cummings Hamiltonian (GJC), realised by a circuit quantum electrodynamics (cQED) system consisting of a…
Calibration of the cross-resonance two-qubit gate between directly-coupled transmons
A. D. Patterson, J. Rahamim, T. Tsunoda +8
Quantum computation requires the precise control of the evolution of a quantum system, typically through application of discrete quantum logic gates on a set of qubits. Here, we us…