Ultracold polar molecules are a promising platform for quantum science and new quantum technologies. Their rich internal structures are ideal for densely storing quantum information and their long-range interactions provide a mechanism for information transfer. However, these properties make molecules highly sensitive to their environment, affecting their coherence and utility in some quantum-science applications.

I will discuss how we can overcome these problems by preparing molecules in an exceptionally controlled environment. We assemble individually trapped ultracold RbCs molecules [1] and transfer them into magic-wavelength optical tweezers. We encode information in the molecular rotational levels and achieve world-leading multisecond coherence times [2].

In this pristine environment, we can resolve and exploit hertz-scale dipolar interactions between pairs of molecules in order to entangle them [3]. We entangle molecules using both spin-exchange interactions and direct microwave excitation and prepare two-molecule Bell states with fidelity 0.924+0.013−0.016. This fidelity is primarily limited by leakage errors. In our experimental platform, we can detect and correct for these errors to achieve a corrected entanglement fidelity 0.976+0.014−0.016. To our knowledge, this represents the highest reported fidelity for molecular entanglement, with second-scale entanglement lifetimes limited solely by these correctable errors. I will also discuss how these entangled molecular pairs can serve as quantum-enhanced sensors of local and global perturbations.

The extension of precise quantum control to complex molecular systems will enable their additional degrees of freedom to be exploited across many domains of quantum science. In particular, long-lived molecular entanglement unlocks opportunities for research in quantum-enhanced metrology, ultracold chemistry, and the use of rotational states in quantum simulation, quantum computation, and as quantum memories.

[1] D. K. Ruttley, A. Guttridge, T. R. Hepworth, and S. L. Cornish, PRX Quantum 5, 020333 (2024).

[2] T. R. Hepworth, D. K. Ruttley, F. von Gierke, P. D. Gregory, A. Guttridge, and S. L. Cornish, Nat. Commun. 16, 7131 (2025).

[3] D. K. Ruttley, T. R. Hepworth, A. Guttridge, and S. L. Cornish, Nature 637, 827 (2025).

A crucial ingredient for scalable fault-tolerant quantum computing is the construction of logical qubits with low error rates and intrinsic noise protection. We propose a cross-platform construction for such hardware-level noise-protection in which the qubits are protected from depolarizing (relaxation) and dephasing errors induced by local noise. Our construction is based on the emergence of collective degrees of freedom from a generalized coherent state construction, similar in spirit to spin coherent states, of a set of entangled spin-1/2 units. The noise protection of the entanglemon qubit is a consequence of a weakly coupled emergent degree of freedom arising due to the non-linear geometry of complex projective space. We present two simple models for entanglemons which are platform agnostic, provide varying levels of protection and in which the qubit basis states are the two lowest energy states with a higher energy gap to other states. We highlight how entanglemons could be realized across a wide range of quantum hardware ranging from superconducting circuits and trapped ion platforms to possibly also quantum Hall skyrmions in graphene and quantum dots in semiconductors. Finally, we present a detailed proposal for the realization of such an entanglemon qubit in superconducting circuits. The inherent noise protection in our models highlights the potential of encoding information in weakly coupled emergent degrees of freedom arising in non-linear geometrical spaces, thereby proposing a different route to achieve scalable fault-tolerance.

The properties of trapped ions make them a pristine platform for simulating the quantum dynamics of spin/electronic and spin-boson/vibronic systems in condensed matter, high-energy physics, and chemical reactions. In these systems, spins/electronic sites and bosons/vibrations can be readily encoded in the internal states of the ions and their collective vibrational modes, respectively, while their interactions can be precisely controlled using electromagnetic fields. By engineering dissipation, environmental effects can be incorporated into the dynamics, enabling studies of non-equilibrium phenomena, providing insights into how these systems behave in their natural settings, and guiding the design of robust quantum technologies. In our laboratory, we use ion-light interactions on dual-species chains of trapped 171Yb+ and 172Yb+ ions to achieve independent control over all Hamiltonian parameters describing the target systems, as well as over the properties of the environment in which they are situated. This approach enables us to experimentally realize paradigmatic models of excitation-energy transfer in condensed-phase environments, which underlie many physical, chemical, and biological processes, from redox catalysis to photosynthesis. In [1], we characterized electron transfer in a donor-acceptor system coupled to a damped collective vibration across different regimes of adiabaticity and identified optimal transfer conditions. In [2], we studied dissipative two-mode linear vibronic coupling systems, exploring charge transfer and vibrationally assisted exciton transfer. We found that the presence of multiple vibrational modes enhances transfer rates and introduces constructively interfering pathways for excitation transfer. Together, these works provide key demonstrations toward a scalable, hardware-efficient approach to using trapped-ion simulators to investigate the dynamics of realistic vibronic systems in condensed-phase environments, essential for informing the development of efficient synthetic light-harvesting devices, bioenergetics, and molecular electronics.

[1] V. So, et al., “Trapped-ion quantum simulation of electron transfer models with tunable dissipation,” Sci. Adv. 10, eads8011 (2024). DOI: 10.1126/sciadv.ads8011.

[2] V. So, et al., “Quantum simulation of charge and exciton transfer in multi-mode models with engineered reservoirs,” arXiv:2505.22729 [quant-ph]

In our quantum gas microscope experiment, we load fermionic 6Li atoms into optical superlattices, and image the local density and spin by performing site-resolved projective measurements [1]. I will present how the exceptional control of optical superlattices and local measurements enables us to perform analog quantum simulation [2] and realize building blocks for digital quantum computation [3, 4].

We conduct systematic experimental quantum simulations of the Fermi-Hubbard model, a key model frequently used to study the physics of high-temperature superconductivity. Using multi-point spin and charge correlators, we perform thermometry, study magnetic polarons and their interactions, and directly observe traces of moving dopants, which are signatures of the strongly correlated states. Furthermore, we identify a universal scaling behavior in magnetic and spin-charge correlations, governed by a doping-dependent energy scale consistent with the pseudogap temperature T*. Comparison with state-of-the-art numerical simulations confirms the quantitative accuracy of our analog quantum simulation [2].

In the digital approach, we implement high-fidelity collisional entangling gates with fermionic atoms in an optical superlattice, achieving Bell state lifetimes beyond 10 s and gate fidelities up to 99.75(6)%. We realize robust pair-exchange gates, enabling local characterization of spin-exchange and pair-tunneling dynamics [4]. These results demonstrate key building blocks for scalable, symmetry-preserving analog-digital hybrid quantum simulators [5, 6, 7].

[1] M. Boll, T. Hilker, F. Salomon, et al. Science 353, 1257-1260 (2016)

[2] T. Chalopin, P. Bojović, S. Wang, et al. arXiv:2412.17801. (2024)

[3] T. Chalopin, P. Bojović, D. Bourgund, et al. Physical Review Letters 134, 053402 (2025).

[4] P. Bojović, T. Hilker, S. Wang, et al. arXiv:2506.14711. (2025)

[5] F. Gkritsis, D. Dux, J. Zhang, et al. Physical Review X Quantum 6, 010318 (2025)

[6] H. Schlömer, H. Lange, T. Franz, et al. Physical Review X Quantum 5, 040341 (2024)

[7] D.K. Mark., H.H. Hu, J. Kwan, et al. arXiv:2412.13186. (2024)

The equations governing the behavior of quantum mechanical systems have been known for around 100 years. Yet, solving these equations is not generically possible on a classical computer and requires either an analog quantum simulator or a digital quantum computer. From the algorithmic side, two main ingredients are crucial for simulating quantum many-body systems: the preparation of suitable quantum states and their precise analysis. I present a toolbox of quantum simulation methods that allow to probe interacting quantum matter on both analog and digital platforms, and highlight recent results on quantum phase estimation that avoid controlled operations—bringing scientifically useful applications within reach of current hardware.

Simulating the dynamics of quantum systems is a challenging task. Tensor networks stand out as a powerful tool in representing quantum states, but are limited by their entanglement content. In this talk, we present some strategies to tame the complexity stemming from time evolution with tensor networks. For one-dimensional systems, we introduce a framework that integrates stabilizer-based techniques directly into matrix product state (MPS) algorithms. These Clifford-enhanced approaches actively disentangle the state during evolution, allowing us to simulate circuit-based and Hamiltonian dynamics with efficiency and accuracy.
In higher dimensions, we leverage the belief propagation algorithm and its variants on lattice specific tensor networks. This technique allows us to keep up with the growth of entanglement in two- and three-dimensional disordered systems, and to probe universal physics, extracting a Kibble-Zurek exponent that aligns with established results.