Anton Frisk Kockum
@antonfkockum.bsky.social
Quantum physicist (associate professor) at Chalmers University of Technology. Angel investor. Chess player and coach.
Overall, we see better logical error suppression per amount of entanglement (ebits) than for other protocols, although it comes at the cost of an increased number of physical qubits to achieve the same code distance.
(7/7)
(7/7)
October 16, 2025 at 6:34 PM
Overall, we see better logical error suppression per amount of entanglement (ebits) than for other protocols, although it comes at the cost of an increased number of physical qubits to achieve the same code distance.
(7/7)
(7/7)
To avoid propagation of errors from the interface, we use an alternating sequence of syndrome-measurement circuits, which may be of independent interest.
(6/7)
(6/7)
October 16, 2025 at 6:33 PM
To avoid propagation of errors from the interface, we use an alternating sequence of syndrome-measurement circuits, which may be of independent interest.
(6/7)
(6/7)
Our protocol is based on an equivalence between Bell measurements and Bell pairs, which can be seen through ZX calculus.
(5/7)
(5/7)
October 16, 2025 at 6:33 PM
Our protocol is based on an equivalence between Bell measurements and Bell pairs, which can be seen through ZX calculus.
(5/7)
(5/7)
New preprint out today with Trond Haug, @timohillmann.bsky.social, and Raphaël Van Laer, at the Wallenberg Centre for Quantum Technology, Chalmers University:
”Lattice surgery with Bell measurements: Modular fault-tolerant quantum computation at low entanglement cost”
arxiv.org/abs/2510.13541
(1/7)
(1/7)
October 16, 2025 at 6:31 PM
New preprint out today with Trond Haug, @timohillmann.bsky.social, and Raphaël Van Laer, at the Wallenberg Centre for Quantum Technology, Chalmers University:
”Lattice surgery with Bell measurements: Modular fault-tolerant quantum computation at low entanglement cost”
arxiv.org/abs/2510.13541
(1/7)
(1/7)
As an application, we show these three-qubit gates could rapidly generate high-fidelity highly entangled GHZ states among three and five giant atoms along a waveguide.
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(6/6)
October 7, 2025 at 11:56 AM
As an application, we show these three-qubit gates could rapidly generate high-fidelity highly entangled GHZ states among three and five giant atoms along a waveguide.
(6/6)
(6/6)
Here, we show that three giant atoms can be tuned to points where they don’t lose any energy into the waveguide, but exchange excitations through the waveguide to implement three-qubit CCZS and DIV gates.
(4/6)
(4/6)
October 7, 2025 at 11:55 AM
Here, we show that three giant atoms can be tuned to points where they don’t lose any energy into the waveguide, but exchange excitations through the waveguide to implement three-qubit CCZS and DIV gates.
(4/6)
(4/6)
New preprint out today with my Marie Curie postdoc Guangze Chen: ”Efficient three-qubit gates with giant atoms”, arxiv.org/abs/2510.04545
(1/6)
(1/6)
October 7, 2025 at 11:54 AM
New preprint out today with my Marie Curie postdoc Guangze Chen: ”Efficient three-qubit gates with giant atoms”, arxiv.org/abs/2510.04545
(1/6)
(1/6)
For single-qubit gates, we find that the serialization overhead generally scales only logarithmically in the number of qubits sharing a drive line. We are able to explain this finding using queueing theory.
(4/5)
(4/5)
August 29, 2025 at 11:32 AM
For single-qubit gates, we find that the serialization overhead generally scales only logarithmically in the number of qubits sharing a drive line. We are able to explain this finding using queueing theory.
(4/5)
(4/5)
We quantify this trade-off and find it to be surprisingly benign. We show that couplers for two-qubit gates can be grouped on common drive lines without any overhead up to a limit set by the connectivity of the qubits.
(3/5)
(3/5)
August 29, 2025 at 11:32 AM
We quantify this trade-off and find it to be surprisingly benign. We show that couplers for two-qubit gates can be grouped on common drive lines without any overhead up to a limit set by the connectivity of the qubits.
(3/5)
(3/5)
We want to limit the number of control lines going into the fridge hosting qubits, to reduce cooling requirements and electronics. But this risks quantum algorithms taking longer to execute and becoming affected by noise, since fewer qubits can be controlled in parallel.
(2/5)
(2/5)
August 29, 2025 at 11:31 AM
We want to limit the number of control lines going into the fridge hosting qubits, to reduce cooling requirements and electronics. But this risks quantum algorithms taking longer to execute and becoming affected by noise, since fewer qubits can be controlled in parallel.
(2/5)
(2/5)
New preprint out today with my PhD student Marvin Richter, together with Ingrid Strandberg and Simone Gasparinetti of the 202Q lab, all at the Wallenberg Centre for Quantum Technology at Chalmers:
”Overhead in quantum circuits with time-multiplexed qubit control”
arxiv.org/abs/2508.20752
(1/5)
”Overhead in quantum circuits with time-multiplexed qubit control”
arxiv.org/abs/2508.20752
(1/5)
August 29, 2025 at 11:30 AM
New preprint out today with my PhD student Marvin Richter, together with Ingrid Strandberg and Simone Gasparinetti of the 202Q lab, all at the Wallenberg Centre for Quantum Technology at Chalmers:
”Overhead in quantum circuits with time-multiplexed qubit control”
arxiv.org/abs/2508.20752
(1/5)
”Overhead in quantum circuits with time-multiplexed qubit control”
arxiv.org/abs/2508.20752
(1/5)
New preprint out today where my PhD student Simon Pettersson Fors and I at WACQT at Chalmers University of Technology, assisted Mustafa Bakr and the team of Peter Leek @ox.ac.uk:
"Intrinsic Multi-Mode Interference for Passive Suppression of Purcell Decay in Superconducting Circuits"
"Intrinsic Multi-Mode Interference for Passive Suppression of Purcell Decay in Superconducting Circuits"
July 15, 2025 at 10:13 AM
New preprint out today where my PhD student Simon Pettersson Fors and I at WACQT at Chalmers University of Technology, assisted Mustafa Bakr and the team of Peter Leek @ox.ac.uk:
"Intrinsic Multi-Mode Interference for Passive Suppression of Purcell Decay in Superconducting Circuits"
"Intrinsic Multi-Mode Interference for Passive Suppression of Purcell Decay in Superconducting Circuits"
Check it out at arxiv.org/abs/2505.23860. My own contribution was mainly on how AI can help quantum computers. (2/2)
June 2, 2025 at 1:18 PM
Check it out at arxiv.org/abs/2505.23860. My own contribution was mainly on how AI can help quantum computers. (2/2)
New preprint out today with many great co-authors from across Europe: ”Quantum computing and artificial intelligence: status and perspectives”. This white paper discusses and explores the various points of intersection between quantum computing and AI. (1/2)
June 2, 2025 at 1:17 PM
New preprint out today with many great co-authors from across Europe: ”Quantum computing and artificial intelligence: status and perspectives”. This white paper discusses and explores the various points of intersection between quantum computing and AI. (1/2)
We see significant improvements over standard QPT in both simulations and experiments for single- and two-qubit gates. (3/3)
May 13, 2025 at 9:56 AM
We see significant improvements over standard QPT in both simulations and experiments for single- and two-qubit gates. (3/3)
New preprint out today with Tangyou Huang, Akshay Gaikwad, Sorin Paraoanu, Giovanna Tancredi, and many others in the experimental and theory teams at WACQT at Chalmers University of Technology and Aalto University: ”Quantum Process Tomography with Digital Twins of Error Matrices” (1/3)
May 13, 2025 at 9:55 AM
New preprint out today with Tangyou Huang, Akshay Gaikwad, Sorin Paraoanu, Giovanna Tancredi, and many others in the experimental and theory teams at WACQT at Chalmers University of Technology and Aalto University: ”Quantum Process Tomography with Digital Twins of Error Matrices” (1/3)
We look at our previously developed XYZ^2 code for quantum error correction (quantum-journal.org/papers/q-202...), show how it can be viewed as a concatenation of a YZZY surface code and a phase-flip parity-check code, and use this to sequentially decode errors, achieving good thresholds. (2/2)
May 7, 2025 at 10:13 AM
We look at our previously developed XYZ^2 code for quantum error correction (quantum-journal.org/papers/q-202...), show how it can be viewed as a concatenation of a YZZY surface code and a phase-flip parity-check code, and use this to sequentially decode errors, achieving good thresholds. (2/2)
New preprint out today with @basudha.bsky.social, Yinzi Xiao, Ben Criger, and Mats Granath, at WACQT, University of Gothenburg, Chalmers University of Technology, @quantinuum.bsky.social: ”Sequential decoding of the XYZ^2 hexagonal stabilizer code” arxiv.org/abs/2505.03691 (1/2)
May 7, 2025 at 10:11 AM
New preprint out today with @basudha.bsky.social, Yinzi Xiao, Ben Criger, and Mats Granath, at WACQT, University of Gothenburg, Chalmers University of Technology, @quantinuum.bsky.social: ”Sequential decoding of the XYZ^2 hexagonal stabilizer code” arxiv.org/abs/2505.03691 (1/2)
New preprint out today with Anikesh Patel, Akshay Gaikwad, Tangyou Huang, and Tahereh Abad, all at the Wallenberg Centre for Quantum Technology (WACQT), at Chalmers University of Technology: ”Selective and efficient quantum state tomography for multi-qubit systems”, arxiv.org/abs/2503.20979
March 28, 2025 at 10:27 AM
New preprint out today with Anikesh Patel, Akshay Gaikwad, Tangyou Huang, and Tahereh Abad, all at the Wallenberg Centre for Quantum Technology (WACQT), at Chalmers University of Technology: ”Selective and efficient quantum state tomography for multi-qubit systems”, arxiv.org/abs/2503.20979
New preprint out today with the experimental group of Io-Chun Hoi in Hong Kong: ”Tunable coherent microwave beam splitter and combiner at the single-photon level”, arxiv.org/abs/2503.20353
March 27, 2025 at 3:55 PM
New preprint out today with the experimental group of Io-Chun Hoi in Hong Kong: ”Tunable coherent microwave beam splitter and combiner at the single-photon level”, arxiv.org/abs/2503.20353