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View article: Non-linear cooling and control of a mechanical quantum harmonic oscillator
Non-linear cooling and control of a mechanical quantum harmonic oscillator Open
Non-linearities are a key feature allowing non-classical control of quantum harmonic oscillators. However, when non-linearities are strong, designing protocols for control is often difficult, placing a barrier to exploiting these propertie…
View article: Quantum Control of a Single <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mn>2</mml:mn><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math> Molecular Ion
Quantum Control of a Single Molecular Ion Open
Science is founded on the benchmarking of theoretical models against experimental measurements, with the challenge that, for all but the simplest systems, the calculations required for high precision become extremely challenging. H2+ is th…
View article: Quantum Control of a Single <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mn>2</mml:mn><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math> Molecular Ion
Quantum Control of a Single Molecular Ion Open
Science is founded on the benchmarking of theoretical models against experimental measurements, with the challenge that, for all but the simplest systems, the calculations required for high precision become extremely challenging. H2+ is th…
View article: Time-adaptive phase estimation
Time-adaptive phase estimation Open
Phase estimation is known to be a robust method for single-qubit gate calibration in quantum computers, while Bayesian estimation is widely used in devising optimal methods for learning in quantum systems. We present a Bayesian method that…
View article: Multizone Trapped-Ion Qubit Control in an Integrated Photonics QCCD Device
Multizone Trapped-Ion Qubit Control in an Integrated Photonics QCCD Device Open
Multiplexed operations and extended coherent control over multiple trapping sites are fundamental requirements for a trapped-ion processor in a large-scale architecture. Here, we demonstrate these building blocks using a surface-electrode …
View article: A 3-dimensional scanning trapped-ion probe
A 3-dimensional scanning trapped-ion probe Open
Single-atom quantum sensors offer high spatial resolution and high sensitivity to electric and magnetic fields. Among them, trapped ions offer exceptional performance in sensing electric fields, which has been used in particular to probe t…
View article: Nonlinear calcium King plot constrains new bosons and nuclear properties
Nonlinear calcium King plot constrains new bosons and nuclear properties Open
Nonlinearities in King plots (KP) of isotope shifts (IS) can reveal the\nexistence of beyond-Standard-Model (BSM) interactions that couple electrons and\nneutrons. However, it is crucial to distinguish higher-order Standard Model\n(SM) eff…
View article: Two-photon cooling of calcium atoms
Two-photon cooling of calcium atoms Open
We demonstrate sub-Doppler cooling of calcium atoms using a two-photon transition from the ${^1}S_0$ ground state to the upper $4s5s~{^1}S_0$ state via the ${^1}P_1$ intermediate state. We achieve temperatures as low as $260~μ\text{K}$ in …
View article: State-dependent control of the motional modes of trapped ions using an integrated optical lattice
State-dependent control of the motional modes of trapped ions using an integrated optical lattice Open
In this work we study the interaction of trapped ions with a state-dependent, high-intensity optical lattice formed above an ion trap chip using integrated photonics. We use a single ion to map the optical potential landscape over many per…
View article: Physical coherent cancellation of optical addressing crosstalk in a trapped-ion experiment
Physical coherent cancellation of optical addressing crosstalk in a trapped-ion experiment Open
We present an experimental investigation of coherent crosstalk cancellation methods for light delivered to a linear ion chain cryogenic quantum register. The ions are individually addressed using focused laser beams oriented perpendicular …
View article: Low-excitation transport and separation of high-mass-ratio mixed-species ion chains
Low-excitation transport and separation of high-mass-ratio mixed-species ion chains Open
We demonstrate low-excitation transport and separation of two-ion crystals consisting of one Be+9 and one Ca+40 ion, with a high mass ratio of 4.4. The full separation involves transport of the mixed-species chain, splitting each ion into …
View article: Modular variable laser cooling for efficient entropy extraction
Modular variable laser cooling for efficient entropy extraction Open
We propose and experimentally demonstrate a method for laser cooling an oscillator based on sequences of spin-state-dependent displacements followed by spin repumping. For a thermal state with mean occupation $\bar{n}\gg 1$ the method atta…
View article: CVsim.jl: Continuous variable quantum system simulation package
CVsim.jl: Continuous variable quantum system simulation package Open
First official release of CVsim.jl It incorporates various state preparation protocols for Schrödinger's cat and Gottesman-Kitaev-Preskill (GKP) states, stabilization schemes for GKP codes, and functions for the calculation of Wigner quasi…
View article: Stabilization of cat-state manifolds using nonlinear reservoir engineering
Stabilization of cat-state manifolds using nonlinear reservoir engineering Open
We introduce a novel reservoir engineering approach for stabilizing multi-component Schrödinger's cat manifolds. The fundamental principle of the method lies in the destructive interference at crossings of gain and loss Hamiltonian terms i…
View article: Physical coherent cancellation of optical addressing crosstalk in a trapped-ion experiment
Physical coherent cancellation of optical addressing crosstalk in a trapped-ion experiment Open
We present an experimental investigation of coherent crosstalk cancellation methods for light delivered to a linear ion chain cryogenic quantum register. The ions are individually addressed using focused laser beams oriented perpendicular …
View article: Time-adaptive phase estimation
Time-adaptive phase estimation Open
Phase estimation is known to be a robust method for single-qubit gate calibration in quantum computers, while Bayesian estimation is widely used in devising optimal methods for learning in quantum systems. We present Bayesian phase estimat…
View article: Grating Design Methodology for Tailored Free-Space Beam-Forming
Grating Design Methodology for Tailored Free-Space Beam-Forming Open
We present a design methodology for free-space beam-forming with general profiles from grating couplers which avoids the need for numerical optimization, motivated by applications in ion trap physics. We demonstrate its capabilities throug…
View article: Penning micro-trap for quantum computing
Penning micro-trap for quantum computing Open
Trapped ions in radio-frequency traps are among the leading approaches for realizing quantum computers, because of high-fidelity quantum gates and long coherence times 1–3 . However, the use of radio-frequencies presents several challenges…
View article: Multi-zone trapped-ion qubit control in an integrated photonics QCCD device
Multi-zone trapped-ion qubit control in an integrated photonics QCCD device Open
Multiplexed operations and extended coherent control over multiple trapping sites are fundamental requirements for a trapped-ion processor in a large scale architecture. Here we demonstrate these building blocks using a surface-electrode t…
View article: Low-excitation transport and separation of high-mass-ratio mixed-species ion chains
Low-excitation transport and separation of high-mass-ratio mixed-species ion chains Open
We demonstrate low-excitation transport and separation of two-ion crystals consisting of one beryllium and one calcium ion, with a high mass ratio of $4.4$. The full separation involves transport of the mixed-species chain, splitting each …
View article: Demonstration of a micro-fabricated Penning trap for quantum computing
Demonstration of a micro-fabricated Penning trap for quantum computing Open
Trapped-ion quantum information processors are among the leading candidates to realise large-scale quantum computing. In trying to scale the number of confined ions in radio-frequency (rf) traps, several challenges arise due to the use of …
View article: Penning micro-trap for quantum computing
Penning micro-trap for quantum computing Open
Trapped ions in radio-frequency traps are among the leading approaches for realizing quantum computers, due to high-fidelity quantum gates and long coherence times. However, the use of radio-frequencies presents a number of challenges to s…
View article: Integration of a high finesse cryogenic build-up cavity with an ion trap
Integration of a high finesse cryogenic build-up cavity with an ion trap Open
We report on the realization of a hemispherical optical cavity with a finesse of F = 13 000 and sustaining inter-cavity powers of 10 kW, which we operate in a closed-cycle cryostat vacuum system close to 4 K. This was designed and built wi…
View article: Grating design methodology for tailored free-space beam-forming
Grating design methodology for tailored free-space beam-forming Open
We present a design methodology for free-space beam-forming with general profiles from grating couplers which avoids the need for numerical optimization, motivated by applications in ion trap physics. We demonstrate its capabilities throug…
View article: Integration of a high finesse cryogenic build-up cavity with an ion trap
Integration of a high finesse cryogenic build-up cavity with an ion trap Open
We report on the realization of a hemispherical optical cavity with a finesse of F = 13000 sustaining inter-cavity powers of 10 kW, which we operate in a closed-cycle cryostat vacuum system close to 4 Kelvin. This was designed and built wi…
View article: Control of an Atomic Quadrupole Transition in a Phase-Stable Standing Wave
Control of an Atomic Quadrupole Transition in a Phase-Stable Standing Wave Open
Using a single calcium ion confined in a surface-electrode trap, we study the interaction of electric quadrupole transitions with a passively phase-stable optical standing wave field sourced by photonics integrated within the trap. We char…
View article: A phonon laser in the quantum regime
A phonon laser in the quantum regime Open
We demonstrate a trapped-ion system with two competing dissipation channels, implemented independently on two ion species co-trapped in a Paul trap. By controlling coherent spin-oscillator couplings and optical pumping rates we explore the…
View article: Trapping and Ground-State Cooling of a Single H$_2^+$
Trapping and Ground-State Cooling of a Single H$_2^+$ Open
We demonstrate co-trapping and sideband cooling of a H$_2^+$ - $^9$Be$^+$ ion pair in a cryogenic Paul trap. We study the chemical lifetime of H$_2^+$ and its dependence on the apparatus temperature, achieving lifetimes of up to $11^{+6}_{…
View article: Control of an atomic quadrupole transition in a phase-stable standing wave
Control of an atomic quadrupole transition in a phase-stable standing wave Open
Using a single calcium ion confined in a surface-electrode trap, we study the interaction of electric quadrupole transitions with a passively phase-stable optical standing wave field sourced by photonics integrated within the trap. We char…