20 April 2026 — Day 1
| Session 1: 09:00 – 09:30 |
Developing modular microwave trapped-ion quantum computers for operation with millions of qubits |
| Prof Winfried Hensinger |
| University of Sussex |
|
Abstract: Microwave technology poses a significant opportunity to scale trapped ion quantum computers to system sizes that support utility scale quantum computation within the fault-tolerant regime. I will present progress on making microwave quantum gates faster with errors much below the fault-tolerant threshold by creating much larger magnetic field gradients. We have successfully developed a new generation of ion microchips capable of generating large magnetic field gradients in excess of 100 T/m. I will show progress on realizing high-fidelity gates with these new chips. We have invented a new approach to generate magnetic field gradient enabling orders of magnitude lower noise, while reducing expected power dissipation for the operation within utility scale-quantum computers and I will report on the first demonstration of this new approach. I will discuss progress in the development of trapped-ion quantum microchips including the integration of atomic ovens into the microchips and materials studies enabling much deeper trap depths in such chips. As an application of our quantum computing research, I will discuss the realisation of a new electric field quantum sensor with unprecedented electric field sensitivities for the measurement of both DC signals and AC signals across a frequency range of sub-Hz to ∼ 500 kHz. |
| Session 2: 09:30 – 10:00 |
Matter-Wave Interferometer of a Trapped Single Ion for a Quantum Sensing Application |
| Prof Takashi Mukaiyama |
| Institute of Science Tokyo |
|
Abstract: Atoms in a coherent superposition of different momentum states enable high-precision measurements of physical quantities. Matter-wave interferometers typically exploit the entanglement between an atomic internal and motional states. The accumulated matter-wave phases along different paths are extracted from the interference signal of the internal states after the final pulse of the interferometer sequence. Achieving precise sensing requires exquisite control over both the internal and external states of individual quantum particles. Atoms and ions are ideal candidates for these applications, as their quantum states can be precisely manipulated using electronic and optical techniques. Here we present our experimental demonstration of matter-wave interferometry of a trapped 171Yb+ ion in a three-dimensional motion, initiated by a momentum kick. We irradiate a mode-locked laser at 355 nm to bring the ion into a superposition of one spin state with no momentum and the other spin state with a momentum, namely a spin-motion entangled state. When the laser is applied along the direction diagonal to any of the trap principal axes, the moving half of the ion wave packet travels in a harmonic potential in a complicated way. After the free evolution time, we irradiate the second laser pulse to close the interferometer. Our experiment successfully observed matter-wave interference of ions in three-dimensional motion by exciting the motion of an ion. To realize a large interferometric area, we developed a technique to significantly expand the ion orbital area by rapidly moving the ion trap center. Additionally, we constructed the entire experimental setup on a rotatable optical table, allowing us to rotate the system for a future trial to detect rotation. |
| Session 3: 10:30 – 11:00 |
Beyond-Ten-Hour Coherence in a Decoherence-Free Clock Qubit |
| Prof Kihwan Kim |
| Tsinghua University |
|
Abstract: Quantum coherence fundamentally limits quantum computer and memory performance. While trapped atomic ions theoretically support million-year coherence based on spontaneous emission, experimental demonstrations have fallen orders of magnitude short. This gap raises whether we face fundamental physical limitations or addressable technical challenges.We combine clock-state qubits with decoherence-free subspace (DFS) encoding to achieve coherence times exceeding ten hours—an order-of-magnitude improvement. Using 171Yb+ ion pairs sympathetically cooled by 138Ba+, we demonstrate this without magnetic shielding or enhanced microwave stabilization. DFS encoding cancels common-mode magnetic fluctuations across micrometer separations while clock states provide environmental insensitivity.Our exponential fits yield a coherence time of 37,750 ± 10,890 seconds. These results experimentally verify that trapped-ion qubits are limited by technical factors rather than fundamental decoherence, establishing a pathway toward ultimate quantum memories for scalable information processing. I will also discuss our related work on scaling up qubit numbers using two-dimensional ion crystals. |
| Session 4: 11:00 – 11:30 |
TBC |
| Prof Umakant Rapol |
| Indian Institute of Science Education and Research, Pune (IISER Pune) |
|
Abstract: TBC |
| Session 5: 11:30 – 12:00 |
Nonlinear and non-Hermitian dynamics with trapped ions and cavity QED |
| Prof Moonjoo Lee |
| Pohang University of Science and Technology (POSTECH) |
|
Abstract: We begin by discussing our experimental study of nonlinear mechanical oscillations in trapped ions. Specifically, we demonstrate the tunability of the Duffing nonlinearity of the ion oscillator, allowing it to transition from the softening to the hardening regime. Furthermore, when the ion velocity exceeds a critical threshold, we observe the formation of a phononic frequency comb in the ion’s motional spectrum. By analyzing the experimental data, we reconstruct the phase-space dynamics and the Poincaré map of the ion motion. The next part focuses on theoretical work with non-Hermitian dynamics arising when a single ion or atom is coupled to an optical resonator. When the strength of coherent interaction balances the dissipation rate, second- or third-order exceptional points can emerge in the system. In addition, we show that introducing a nanotip into the mode of a Fabry-Perot-type resonator enables controlled tuning of the dissipation rate. This capability allows us to generate an exceptional line and realize a dissipation-induced topological transition, in which the exceptional point can be tuned solely through the control of dissipation. Finally, we present our experiments with a chain of approximately 100 ions. The ions can be individually manipulated and cooled close to their motional ground state. We discuss experiments on phonon hopping in the ion chain, as well as measurements of both the local and global density of states. |
| Session 6: 14:00 – 14:30 |
Scalable and High-Fidelity Quantum Entanglement in Trapped-Ion Systems |
| Prof Taeyoung Choi |
| Ewha Womans University |
|
Abstract: Achieving high-fidelity and scalable entanglement is one of the central challenges in realizing quantum error correction and building a practical quantum computer. Among various physical platforms, trapped-ion systems have emerged as a particularly successful approach for precise control of quantum states, enabling high-fidelity single-qubit operations and two-qubit entangling gates for quantum computation and simulation. In this talk, I will focus on the challenges of scaling up trapped-ion systems from both hardware and software perspectives, including increasing the number of qubits and improving gate performance through various modulation techniques. I will also introduce several ongoing research topics in our laboratory aimed at developing scalable and practical trapped-ion–based quantum processors. |
| Session 7: 14:30 – 15:00 |
Superconducting ion traps |
| Prof Atsushi Noguchi |
| The University of Tokyo & RIKEN |
|
Abstract: Recent experiments in trapped-ion platforms have demonstrated two-qubit gate fidelities reaching 99.99% using RF-based quantum gates. Because gate fidelity directly determines the achievable performance and scalability of quantum computers, a central challenge is how to realize such ultra-high-fidelity gates in a scalable architecture. To enhance the scalability of RF-based gates, we employ high-Q resonators fabricated from superconducting thin films. A high-Q resonator effectively enhances the circulating current in the circuit, enabling the generation of large magnetic-field gradients at the ion position with high efficiency relative to the input drive power. This approach allows strong spin–motion coupling while significantly reducing the required microwave power. Furthermore, by integrating superconducting cavities, the RF voltages for ion trapping can be achieved with substantially lower input power, providing a pathway toward energy-efficient and scalable trapped-ion systems. In addition to presenting detailed results of our superconducting-resonator–based RF gate architecture, we will also discuss our ongoing efforts toward an alternative platform: an electron-trap quantum computer, in which single electrons are confined in vacuum and coupled to superconducting circuits. This hybrid approach opens new possibilities for compact, strongly coupled, and scalable quantum information processing. |
| Session 8: 15:00 – 15:30 |
Programmable quantum simulation of anharmonic dynamics |
| Dr Cameron McGarry |
| University of Sydney |
|
Abstract: Continuous-variable–discrete-variable (CV–DV) quantum simulators offer a natural route to simulating bosonic dynamics relevant to many branches of physics and chemistry. However, programmable simulation of arbitrary dynamics is an outstanding challenge. In particular, simulating anharmonic dynamics, which is ubiquitous across the physical sciences, is challenging due to the highly harmonic nature of oscillators used in CV–DV simulators. Here, we experimentally demonstrate programmable CV–DV quantum simulation of anharmonic dynamics in a range of double-well potentials, implemented in a trapped-ion system. We synthesise the time-evolution operators using a bosonic-quantum-signal-processing subroutine, which allows the potential to be tuned between experiments by controlling classical experimental parameters. We observe coherent dynamics in various double-well potentials, where a wavepacket tunnels through the potential barrier, and we suppress this effect by programmatically introducing asymmetry. |