We’re hosting the 3rd International Workshop on Quantum Optics with Giant Atomic Emitters at Chalmers University of Technology in Gothenburg on 27-29 May 2026. There will be invited and contributed talks, as well as a poster session. Welcome! www.chalmers.se/en/current/c...
Controlling unwanted long-range qubit couplings is crucial when scaling up. We provide theoretical methods to create a comprehensive picture of these couplings, complemented by experimental measurements, which can inform design of large superconducting quantum processors.
(6/6)
In the second preprint, in collaboration with the group of Mustafa Bakr and Peter Leek at Oxford University, we studied how couplings between superconducting qubits scale across a large device.
(5/6)
These benchmarks are designed to assess holistic system performance and to be scalable such that they can cover both noisy-intermediate scale quantum computers and fault-tolerant quantum computers.
(4/6)
We propose four benchmarks:
* Clifford Volume
* GHZ-state preparation
* Shor’s period-finding algorithm
* Quantum error correction for Bell states
(3/6)
In the first, the teams of the EU quantum-computing projects OpenSuperQPlus, Millenion, and SPINUS came together to define a suite of benchmarks to help us assess the development of quantum computers. These benchmarks are developed to be KPIs for the EU Quantum Flagship.
(2/6)
Two new preprints out today in the rush before Christmas:
”The EU Quantum Flagship’s key performance indicators for quantum computing”
arxiv.org/abs/2512.19653
”Crosstalk dispersion and spatial scaling in superconducting qubit arrays”
arxiv.org/abs/2512.18148
(1/6)
I have a PhD position open in my group on the topic of “characterization of large-scale quantum computers”:
www.chalmers.se/en/about-cha...
Application deadline 8 March. Please help spread the word to good candidates!
This extends ideas from earlier work we did a few years ago with superconducting qubits in front of a mirror: journals.aps.org/prl/abstract...
(3/3)
We show that magnons in spin ensembles [yttrium iron garnet (YIG) spheres] along a waveguide can be selectively strongly coupled to each other by exploiting interference effects from a mirror at the end of the waveguide.
(2/3)
New preprint out last week with the group of Io-Chun Hoi at the City University of Hong Kong:
”Realizing on-demand all-to-all selective interactions between distant spin ensembles”
arxiv.org/abs/2512.07326
(1/3)
Now published in Physical Review Letters! @physrevlett.bsky.social
journals.aps.org/prl/abstract...
The many-body BICs we propose here should be accessible for state-of-the-art experiments using superconducting circuits.
(4/4)
Such spatially localised states in a continuum have previously mostly been studied for single photons/excitations.
(3/4)
We show that bound states in the continuum (BICs) can form with strongly correlated two-photon states, so-called doublons, in setups with atoms coupling at multiple points to a waveguide.
(2/4)
New preprint out today with my postdoc @guangzechen.bsky.social and Walter Rieck, at Chalmers University of Technology and the Wallenberg Centre for Quantum Technology:
”Doublon bound states in the continuum through giant atoms”
arxiv.org/abs/2511.18212
(1/4)
Our Python libraries for quantum state, process, and measurement tomography are freely available to use:
github.com/mstorresh/GD...
github.com/quantshah/gd...
github.com/agtomo/SGD-QMT
(5/5)
We now show how these data-processing methods also work well for extracting the POVM elements that characterise a measurement device.
(4/5)
We have previously developed and demonstrated such data-processing methods for quantum state and process tomography:
doi.org/10.1088/2058...
doi.org/10.1103/Phys...
(3/5)
In this work, we complete the tomography trio (state, process, and measurement tomography) with gradient-descent-based data-processing methods.
(2/5)
New preprint out this week with my postdoc @Akshay Gaikwad and Sebastian Torres:
”Quantum measurement tomography with mini-batch stochastic gradient descent”
arxiv.org/abs/2511.15682
(1/5)
Adding more physical coupling point to create an actual giant atom, we can make the scattering unidirectional and the conversion into a desired multi-photon state perfect.
(5/5)
The states with different numbers of photons naturally separate in space due to having different group velocities.
(4/5)
The scattering potential becomes nonlocal due to the spatial extension of the multi-photon states; we term this a pseudo-giant atom.
(3/5)
We show how correlated two- and three-photon states (doublons and triplons) can be generated by scattering an incoming single photon off excited two-level emitters in a nonlinear waveguide.
(2/5)
New preprint out today together with Jia-Qi Li and Xin Wang at Xi’an Jiaotong University: ”Generating spatially separated correlated multiphoton states in nonlinear waveguide quantum electrodynamics” arxiv.org/abs/2511.14281
(1/5)
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)
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)
Our protocol is based on an equivalence between Bell measurements and Bell pairs, which can be seen through ZX calculus.
(5/7)
