@article{Patscheider_ScattLen_2021,

title = {Accurate determination of the scattering length of erbium atoms},

author = {A. Patscheider and L. Chomaz and G. Natale and D. Petter and M. J. Mark and S. Baier and B. Yang and R. R. W. Wang and J. L. Bohn and F. Ferlaino},

url = {https://arxiv.org/abs/2112.11883},

year  = {2021},

date = {2021-12-22},

urldate = {2021-12-22},

journal = {arXiv},

volume = {arXiv:2112.11883},

abstract = {An accurate knowledge of the scattering length is fundamental in ultracold quantum gas experiments and essential for the characterisation of the system as well as for a meaningful comparison to theoretical models. Here, we perform a careful characterisation of the s-wave scattering length as for the four highest-abundance isotopes of erbium, in the magnetic field range from 0G to 5G. We report on cross-dimensional thermalization measurements and apply the Enskog equations of change to numerically simulate the thermalization process and to analytically extract an expression for the so-called number of collisions per re-thermalization (NCPR) to obtain as from our experimental data. We benchmark the applied cross-dimensional thermalization technique with the experimentally more demanding lattice modulation spectroscopy and find good agreement for our parameter regime. Our experiments are compatible with a dependence of the NCPR with as, as theoretically expected in the case of strongly dipolar gases. Surprisingly, we experimentally observe a dependency of the NCPR on the density, which might arise due to deviations from an ideal harmonic trapping configuration. Finally, we apply a model for the dependency of the background scattering length with the isotope mass, allowing to estimate the number of bound states of erbium.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bradley_Memory_2021,

title = {Robust quantum-network memory based on spin qubits in isotopically engineered diamond},

author = {C. E. Bradley and S. W. Bone and P. F. W. Moller and S. Baier and M. J. Degen and S. J. H. Loenen and H. P. Bartling and M. Markham and D. J. Twitchen and R. Hanson and D. Elkouss and T. H. Taminiau},

url = {https://arxiv.org/abs/2111.09772},

year  = {2021},

date = {2021-11-18},

urldate = {2021-11-18},

journal = {arXiv},

volume = {arXiv:2111.09722},

abstract = {Quantum networks can enable long-range quantum communication and modular quantum computation. A powerful approach is to use multi-qubit network nodes which provide the quantum memory and computational power to perform entanglement distillation, quantum error correction, and information processing. Nuclear spins associated with optically-active defects in diamond are promising qubits for this role. However, their dephasing during entanglement distribution across the optical network hinders scaling to larger systems. In this work, we show that a single 13C spin in isotopically engineered diamond offers a long-lived quantum memory that is robust to the optical link operation of an NV centre. The memory lifetime is improved by two orders-of-magnitude upon the state-of-the-art, and exceeds the best reported times for remote entanglement generation. We identify ionisation of the NV centre as a newly limiting decoherence mechanism. As a first step towards overcoming this limitation, we demonstrate that the nuclear spin state can be retrieved with high fidelity after a complete cycle of ionisation and recapture. Finally, we use numerical simulations to show that the combination of this improved memory lifetime with previously demonstrated entanglement links and gate operations can enable key primitives for quantum networks, such as deterministic non-local two-qubit logic operations and GHZ state creation across four network nodes. Our results pave the way for test-bed quantum networks capable of investigating complex algorithms and error correction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Hermans_teleport_2021,

title = {Qubit teleportation between non-neighboring nodes in a quantum network},

author = {S. L. N. Hermans and M. Pompili and H. K. C. Beukers and S. Baier and J. Borregaard and R. Hanson},

url = {https://arxiv.org/abs/2110.11373#},

year  = {2021},

date = {2021-10-21},

urldate = {2021-10-21},

journal = {arXiv},

volume = {arXiv:2110.11373},

abstract = {Future quantum internet applications will derive their power from the ability to share quantum information across the network. Quantum teleportation allows for the reliable transfer of quantum information between distant nodes, even in the presence of highly lossy network connections. While many experimental demonstrations have been performed on different quantum network platforms, moving beyond directly connected nodes has so far been hindered by the demanding requirements on the pre-shared remote entanglement, joint qubit readout and coherence times. Here we realize quantum teleportation between remote, non-neighboring nodes in a quantum network. The network employs three optically connected nodes based on solid-state spin qubits. The teleporter is prepared by establishing remote entanglement on the two links, followed by entanglement swapping on the middle node and storage in a memory qubit. We demonstrate that once successful preparation of the teleporter is heralded, arbitrary qubit states can be teleported with fidelity above the classical bound, even with unit efficiency. These results are enabled by key innovations in the qubit readout procedure, active memory qubit protection during entanglement generation and tailored heralding that reduces remote entanglement infidelities. Our work demonstrates a prime building block for future quantum networks and opens the door to exploring teleportation-based multi-node protocols and applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Pompili259,

title = {Realization of a multinode quantum network of remote solid-state qubits},

author = {M. Pompili* and S. L. N. Hermans* and S. Baier* and H. K. C. Beukers and P. C. Humphreys and R. N. Schouten and R. F. L. Vermeulen and M. J. Tiggelman and L. Santos Martins and B. Dirkse and S. Wehner and R. Hanson and *equal contribution},

url = {https://science.sciencemag.org/content/372/6539/259},

doi = {10.1126/science.abg1919},

issn = {0036-8075},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {Science},

volume = {372},

number = {6539},

pages = {259--264},

publisher = {American Association for the Advancement of Science},

abstract = {Future quantum networks will provide the means to develop truly secure communication channels and will have applications in many other quantum-based technologies. In this work we present a three-node remote quantum network based on solid-state spin qubits (nitrogen-vacancy centers in diamond) coupled by photons. The implementation of two quantum protocols on the network. entanglement distribution and entanglement swapping, illustrates a key platform for exploring, testing, and developing multinode quantum networks and quantum protocols. 

},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevLett.125.193601,

title = {Orbital and Spin Dynamics of Single Neutrally-Charged Nitrogen-Vacancy Centers in Diamond},

author = {S. Baier* and C. E. Bradley* and T. Middelburg and V. V. Dobrovitski and T. H. Taminiau and R. Hanson and *equal contribution},

url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.193601},

doi = {10.1103/PhysRevLett.125.193601},

year  = {2020},

date = {2020-11-01},

urldate = {2020-11-01},

journal = {Phys. Rev. Lett.},

volume = {125},

pages = {193601},

publisher = {American Physical Society},

abstract = {The neutral charge state plays an important role in quantum information and sensing applications based on nitrogen-vacancy centers. However, the orbital and spin dynamics remain unexplored. Here, we use resonant excitation of single centers to directly reveal the fine structure, enabling selective addressing of spin-orbit states. Through pump-probe experiments, we find the orbital relaxation time (430 ns at 4.7 K) and measure its temperature dependence up to 11.8 K. Finally, we reveal the spin relaxation time (1.5 s) and realize projective high-fidelity single-shot readout of the spin state (≥98%).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{PhysRevResearch.2.023050,

title = {Controlling dipolar exchange interactions in a dense three-dimensional array of large-spin fermions},

author = {A. Patscheider and B. Zhu and L. Chomaz and D. Petter and S. Baier and A. -M. Rey and F. Ferlaino and M. J. Mark},

url = {https://link.aps.org/doi/10.1103/PhysRevResearch.2.023050},

doi = {10.1103/PhysRevResearch.2.023050},

year  = {2020},

date = {2020-04-01},

urldate = {2020-04-01},

journal = {Phys. Rev. Research},

volume = {2},

pages = {023050},

publisher = {American Physical Society},

abstract = {Dipolar interactions are ubiquitous in nature and rule the behavior of a broad range of systems spanning from energy transfer in biological systems to quantum magnetism. Here we study magnetization-conserving dipolar induced spin-exchange dynamics in dense arrays of fermionic erbium atoms confined in a deep three-dimensional lattice. Harnessing the special atomic properties of erbium, we demonstrate control over the spin dynamics by tuning the dipole orientation and changing the initial spin state within the large 20-spin hyperfine manifold. Furthermore, we demonstrate the capability to quickly turn on and off the dipolar exchange dynamics via optical control. The experimental observations are in excellent quantitative agreement with numerical calculations based on discrete phase-space methods, which capture entanglement and beyond-mean-field effects. Our experiment sets the stage for future explorations of rich magnetic behaviors in long-range interacting dipoles, including exotic phases of matter and applications for quantum information processing.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}