Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum Computing, Communication, and Simulation

Individual addressing of trapped ions for UV-based quantum gate operations

Marcus Babin, Erik Beckert, Peter Schreiber, Felix Kraze, Simone Fabian

Published Mar 8, 2023• 0 citations
Publisher

Abstract

With the emergence of different quantum computers approaches, ion-trapped based quantum processors offer a promising concept with coherence times of over 2 s and gate times of 10 to 80 µs with fidelities of over 99.9%. In such systems, ions are being held inside a linear quadrupole trap in defined position zones. The laser induced qubit rotation, initialization and readout operations require an ion individual addressing unit. Our hardware is able to create individual laser foci for 10 captured ions with beam waists of 1.1 µm. Qubit manipulations are realized with a laser wavelength of 396 nm employing 40Ca+ ions.

DOI
10.1117/12.2651901

Related papers

UV laser-based addressing unit for trapped-ion quantum computers

Marcus Babin, Erik Beckert, Peter Schreiber +2 more

Laser-based addressing units are core components for trapped-ion quantum computers, in which ions are held in defined, separate, micron-scale position fields and are brought into different qubit states via an addressing beam with an ion-specific wavelength. The spin of the valence electrons of the atomic ions represents the qubits states. An addressing action causes a stimulated Raman transition, which in turn causes a change in electron spin and thus a qubit rotation. Our unit is designed for 10 40Ca+ ions kept in a linear microchip ion trap. The hardware platform utilizes waveguides with integrated collimating micro lenses, followed by a cascaded 4f optical setup, consisting of a focusing and a beam expander unit. An aspherical lens realizes a lateral shift tolerant focus inside the trap. The addressing unit achieves minimal foci beam waists of 1.1 μm, with a minimal ion separation of 5.31 μm. The operating addressing wavelength ranges from 395 nm to 405 nm. Fault relevant ion crosstalk ratio is less than 10−4. Addressing operations can be conducted in parallel on all captured ions. The specified laser-based addressing unit provides a stable and low-error solution for qubit operations with coherence times of several seconds. Further adaptions of the waveguide structures and the implementation of micro optical lenses offer the potential of fully integrating the system into the microchip ion trap. Such a quasi-monolithic trap integration constitutes a compact, and highly scalable addressing and detection system with the ability to address as many qubit registers as the ion trap capacity allows.

Quantum Technology: Driving Commercialisation of an Enabling Science•Jan 11, 2023•1 citation

A scalable PIC-based addressing unit for segmented quadrupole ion traps

Erik Beckert, Marcus Babin, Michael Reibe +6 more

Scalability is crucial for quantum computing to achieve high computing performance and ultimately true quantum advantage. Such a quantum computing platform requires elements to be replicated reliably within an extendable system framework. Photonic integrated circuits (PICs) allow the conversion of inputs in an accurate process due to the employment of lithographic production techniques. We present an addressing unit for ion-based quantum computing employing PICs that are arranged for multiple addressing zones inside a segmented ion-trap chip. The addressing unit is designed for individual and parallel addressing of single ions inside a chain of ten ions held by one trap segment. At PIC level, each addressing beam is realized with one waveguide channel and its mode field adapted to be optimal for imaging onto a trap segment. An additional imaging system in the same formfactor as the PIC, couples optically in free space from the waveguide channel to the individual ions. It is based on wafer-level microlenses combined in one stack and forms one unit with the PIC. Such a hardware-based capability eventually allows precise gate operations that are necessary for a universal quantum computer.

Quantum Computing, Communication, and Simulation•Mar 5, 2026•0 citations

Laser optics for the manipulation and readout of single atomic ions

Michael Reibe, Marcus Babin, Simone Fabian +3 more

Ion-trapped-based quantum computers offer long coherence times of over 2 seconds with high fidelity and hence constitute a promising architecture for realizing quantum computer systems beyond the NISQ classification. Utilizing a fiber-coupled laser source at a wavelength of 396 nm our setup is able to manipulate any combination of 40Ca+ ions inside a coherent chain of 10 ions simultaneously, while also being able to collect the readout of each individual ion. Our setup achieves an ion-sided mode field diameter of less than 2 μm and a pointing accuracy of 250 nm for one chain of ions. A micro-lens integrated waveguide carrier chip with linear optics is used to create 10 separate laser beams at the actual ion dimensions. The modularity of the systems allows the system to be arranged onto additional linked ion trap chains, pathing the way for a scalable quantum computer.

Quantum Computing, Communication, and Simulation•Mar 12, 2024•0 citations

Integrated and fiber-coupled imaging system for the addressing of single ions

Marcus Babin, Michael Reibe, Steffen Trautmann +3 more

In trapped-ion-based quantum computing, logic gates are performed by laser addressing ions with a specific wavelength to manipulate its quantum state. We present a trap-integrated addressing unit that is ultra-high vacuum compatible and quasi-monolithically bonded onto the trap substrate. Our setup is based on a quadrupole trap for containing a chain of ten calcium ion. A fiber-coupled aluminum oxide waveguide chip emits ten addressing beams at 405 nm, that are imaged by a micro-optical lens stack onto the ion trap axis. The setup allows to address each ion individually and in parallel. Imaging transmission losses are below 2 dB with an ion-addressing spot diameter of 1 µm at 1/e^2 intensity and a Strehl ratio above 0.9 for all ten beams. With an inner minimum ion spacing of 5 µm and a total chain length of approximately 60 µm, the addressing beam crosstalk ratio is less than one percent.

SPIE Quantum Information Science, Sensing, and Computation•May 30, 2025•0 citations

Parallel Transport Quantum Logic Gates with Trapped Ions

Ludwig E. de Clercq, Hsiang-Yu Lo, Matteo Marinelli +6 more

We demonstrate single-qubit operations by transporting a beryllium ion with a controlled velocity through a stationary laser beam. We use these to perform coherent sequences of quantum operations, and to perform parallel quantum logic gates on two ions in different processing zones of a multiplexed ion trap chip using a single recycled laser beam. For the latter, we demonstrate individually addressed single-qubit gates by local control of the speed of each ion. The fidelities we observe are consistent with operations performed using standard methods involving static ions and pulsed laser fields. This work therefore provides a path to scalable ion trap quantum computing with reduced requirements on the optical control complexity.

arXiv:1509.06624•Physical Review Letters•Feb 24, 2016•32 citations

Addressing and Cooling of Single Ions in Paul Traps

Hanns‐Christoph Nägerl, Christian F. Roos, H. J. Rohde +4 more

The use of cold trapped ions for quantum information processing requires the preparation of linear strings of ions at low temperatures and the coherent manipulation by laser light of the quantum state of individual ions in the string. In our experiment, 40Ca+ ions are trapped in a linear Paul trap, forming crystallized linear strings when laser cooled. These strings are observed by fluorescence detection on the S1/2-P1/2 dipole transition at 397 nm using a photomultiplier and a CCD camera. The narrow S1/2-D5/2 quadrupole transition at 729 nm is used to investigate and manipulate the vibrational motion of the ion in the trap. The spectral resolution obtained up to now on this transition is 2 · 10—12, proving long coherence time of the two-level system. Addressing of individual ions in the string is achieved, using a tightly focused laser beam at 729 nm, and detected by the observation of quantum jumps from the S1/2 to the D5/2 level. These experimental techniques make ions in a superposition of their S1/2 and D5/2 states suitable as qubits for quantum information processing. The realization of a two-ion quantum gate furthermore requires ground-state cooling of the string. The status of current experiments is reviewed and techniques to achieve ground-state cooling of ion strings are discussed.

Fortschritte der Physik•May 1, 2000•18 citations
With the emergence of different quantum computers approaches, ion-trapped based quantum processors offer a promising concept with coherence times of over 2 s and gate times of 10 to 80 µs with fidelities of over 99.9%. In such systems, ions are being held inside a linear quadrupole trap in defined position zones. The laser induced qubit rotation, initialization and readout operations require an ion individual addressing unit. Our hardware is able to create individual laser foci for 10 captured ions with beam waists of 1.1 µm. Qubit manipulations are realized with a laser wavelength of 396 nm employing 40Ca+ ions.
Laser-based addressing units are core components for trapped-ion quantum computers, in which ions are held in defined, separate, micron-scale position fields and are brought into different qubit states via an addressing beam with an ion-specific wavelength. The spin of the valence electrons of the atomic ions represents the qubits states. An addressing action causes a stimulated Raman transition, which in turn causes a change in electron spin and thus a qubit rotation. Our unit is designed for 10 40Ca+ ions kept in a linear microchip ion trap. The hardware platform utilizes waveguides with integrated collimating micro lenses, followed by a cascaded 4f optical setup, consisting of a focusing and a beam expander unit. An aspherical lens realizes a lateral shift tolerant focus inside the trap. The addressing unit achieves minimal foci beam waists of 1.1 μm, with a minimal ion separation of 5.31 μm. The operating addressing wavelength ranges from 395 nm to 405 nm. Fault relevant ion crosstalk ratio is less than 10−4. Addressing operations can be conducted in parallel on all captured ions. The specified laser-based addressing unit provides a stable and low-error solution for qubit operations with coherence times of several seconds. Further adaptions of the waveguide structures and the implementation of micro optical lenses offer the potential of fully integrating the system into the microchip ion trap. Such a quasi-monolithic trap integration constitutes a compact, and highly scalable addressing and detection system with the ability to address as many qubit registers as the ion trap capacity allows.
Scalability is crucial for quantum computing to achieve high computing performance and ultimately true quantum advantage. Such a quantum computing platform requires elements to be replicated reliably within an extendable system framework. Photonic integrated circuits (PICs) allow the conversion of inputs in an accurate process due to the employment of lithographic production techniques. We present an addressing unit for ion-based quantum computing employing PICs that are arranged for multiple addressing zones inside a segmented ion-trap chip. The addressing unit is designed for individual and parallel addressing of single ions inside a chain of ten ions held by one trap segment. At PIC level, each addressing beam is realized with one waveguide channel and its mode field adapted to be optimal for imaging onto a trap segment. An additional imaging system in the same formfactor as the PIC, couples optically in free space from the waveguide channel to the individual ions. It is based on wafer-level microlenses combined in one stack and forms one unit with the PIC. Such a hardware-based capability eventually allows precise gate operations that are necessary for a universal quantum computer.
Ion-trapped-based quantum computers offer long coherence times of over 2 seconds with high fidelity and hence constitute a promising architecture for realizing quantum computer systems beyond the NISQ classification. Utilizing a fiber-coupled laser source at a wavelength of 396 nm our setup is able to manipulate any combination of 40Ca+ ions inside a coherent chain of 10 ions simultaneously, while also being able to collect the readout of each individual ion. Our setup achieves an ion-sided mode field diameter of less than 2 μm and a pointing accuracy of 250 nm for one chain of ions. A micro-lens integrated waveguide carrier chip with linear optics is used to create 10 separate laser beams at the actual ion dimensions. The modularity of the systems allows the system to be arranged onto additional linked ion trap chains, pathing the way for a scalable quantum computer.
In trapped-ion-based quantum computing, logic gates are performed by laser addressing ions with a specific wavelength to manipulate its quantum state. We present a trap-integrated addressing unit that is ultra-high vacuum compatible and quasi-monolithically bonded onto the trap substrate. Our setup is based on a quadrupole trap for containing a chain of ten calcium ion. A fiber-coupled aluminum oxide waveguide chip emits ten addressing beams at 405 nm, that are imaged by a micro-optical lens stack onto the ion trap axis. The setup allows to address each ion individually and in parallel. Imaging transmission losses are below 2 dB with an ion-addressing spot diameter of 1 µm at 1/e^2 intensity and a Strehl ratio above 0.9 for all ten beams. With an inner minimum ion spacing of 5 µm and a total chain length of approximately 60 µm, the addressing beam crosstalk ratio is less than one percent.
We demonstrate single-qubit operations by transporting a beryllium ion with a controlled velocity through a stationary laser beam. We use these to perform coherent sequences of quantum operations, and to perform parallel quantum logic gates on two ions in different processing zones of a multiplexed ion trap chip using a single recycled laser beam. For the latter, we demonstrate individually addressed single-qubit gates by local control of the speed of each ion. The fidelities we observe are consistent with operations performed using standard methods involving static ions and pulsed laser fields. This work therefore provides a path to scalable ion trap quantum computing with reduced requirements on the optical control complexity.
The use of cold trapped ions for quantum information processing requires the preparation of linear strings of ions at low temperatures and the coherent manipulation by laser light of the quantum state of individual ions in the string. In our experiment, 40Ca+ ions are trapped in a linear Paul trap, forming crystallized linear strings when laser cooled. These strings are observed by fluorescence detection on the S1/2-P1/2 dipole transition at 397 nm using a photomultiplier and a CCD camera. The narrow S1/2-D5/2 quadrupole transition at 729 nm is used to investigate and manipulate the vibrational motion of the ion in the trap. The spectral resolution obtained up to now on this transition is 2 · 10—12, proving long coherence time of the two-level system. Addressing of individual ions in the string is achieved, using a tightly focused laser beam at 729 nm, and detected by the observation of quantum jumps from the S1/2 to the D5/2 level. These experimental techniques make ions in a superposition of their S1/2 and D5/2 states suitable as qubits for quantum information processing. The realization of a two-ion quantum gate furthermore requires ground-state cooling of the string. The status of current experiments is reviewed and techniques to achieve ground-state cooling of ion strings are discussed.