Emerging Technologies for Scaling Trapped-ion Quantum Systems Workshop

ABSTRACT

Trapped ions show great promise as candidate qubits for quantum information processors as well as the stable references for precise, portable atomic clocks. The trapped-ion quantum platform at MIT Lincoln Laboratory is built upon a number of different integrated control technologies in service of both of these applications. Although the system requirements for quantum computers and optical atomic clocks differ in some respects, we have taken advantage of several fruitful synergies to improve the performance of both aspects of our technological platform. In this workshop, I will present some of our recent trapped-ion work, including integrated optical addressing, fluorescence light detection, and electronic control, and also discuss future directions for these efforts.

BIO

Colin Bruzewicz is a member of the Technical Staff in the Quantum Information and Integrated Nanosystems Group at MIT Lincoln Laboratory in Lexington, MA. His research interests include the application of advanced technologies and techniques to trapped ions for quantum information processing. In addition to the integration of key control technologies into microfabricated ion traps, the trapped-ion group at Lincoln Laboratory also investigates sources of deleterious electric-field noise, multi-species quantum logic primitives, and novel qubit encodings based on multi-level atomic systems.

ABSTRACT

A transport-enabled entangling gate and exchange cooling with trapped ions

Kenton Brown, Holly Tinkey, Spencer Fallek, Craig Clark, John Gray, Ryan McGill, Vikram Sandhu, Brian Sawyer

We perform a two-qubit entangling Molmer-Sorensen gate by transporting two co-trapped 40Ca+ ions in a linear surface Paul trap through a stationary, bichromatic laser beam. We measure the Doppler shift of the ions during different segments of transport, observe variations in ion velocity, and correct for these variations using modifications to the temporal interpolation of the moving trap potential (waveform). We compensate for time-dependent ac Stark shifts during transport with additional dynamic adjustments of the transport waveform to realize a variable Doppler shift. We compare the performance of these transport gates to those realized in stationary potentials. In related work, we experimentally study the technique of dynamic exchange cooling. This protocol utilizes a bank of cold ions to cool hotter computational ions, where coolant and computational ions are of the same atomic species. The Coulomb interaction mediates an energy exchange between a coolant ion and a computational ion. We test this concept with two ions, showing that the process is efficient and fast. We remove over 96% (as many as 100 quanta) of axial motional energy from a computational ion. The resonant energy transfer to a coolant ion takes just 5.8 µs. These experiments demonstrate the potential of actively integrating transport into quantum information operations. This work was done in collaboration with Los Alamos National Laboratory.

BIO

Kenton R. Brown is the Chief Scientist of the Quantum Systems Division at the Georgia Tech Research Institute, where he leads efforts to advance the primitive operations and core technologies that will enable ion trap quantum computing. His primary research interest is the study of simple physical systems at the quantum level. As a graduate researcher with Dr. Bruce E. Kane he concentrated on low-noise, cryogenic measurements of nanoelectrical devices. One of his accomplishments was the development of a scanning force microscope operating at millikelvin temperatures, the first of its kind. As a postdoctoral research with Nobel Prize winner Dr. David J. Wineland, he implemented an experiment to suppress the thermal vibrations of a microscopic silicon cantilever with radio-frequency electrical forces. He also executed the first experiment to directly couple harmonic oscillators (realized as trapped ions) in separate locations at the quantum level. More recently he has refined strategies to achieve high quantum gate fidelities, having demonstrated the highest fidelity one-qubit gate (at that time) in 2011 and the highest two-qubit gate fidelity in 2021. He has also developed design and modeling techniques for microfabricated ion traps and has used these to implement high-speed ion transport and the first-ever entangling gate performed on ions in a moving potential.

ABSTRACT

Quantum information processors and atomic clocks based on trapped ions continue to scale towards greater I/O, size, and power requirements. These demands motivate the replacement of external optical conditioning elements, such as amplitude, phase, frequency modulators, with integrated versions. We present the design, fabrication, and implementation of a monolithically integrated piezo-optomechanical Mach-Zehnder modulator with a microfabricated surface ion trap. We have demonstrated single qubit gate fidelities better that 99.7% with this design^[1].  In addition, we describe advances in fabrication and electrical control that have enabled us to realize larger and more capable ion traps for quantum computing^[2].

[1] C.W. Hogle, et al., Nature Quantum Information 9, 74 (2023). [2] J.D. Sterk, et al. Nature Quantum Information 8, 68 (2022).

BIO

Dr. Daniel Stick is a Distinguished Member of Technical Staff at Sandia National Labs. His research focuses on developing innovative technologies around atomic and quantum systems, including micro-fabricated surface ion traps for quantum information applications. This work includes the design and fabrication of the traps, as well as experiments with storing, transporting, and performing quantum gates on ions. Dr. Stick received his BS from Caltech and his PhD from the University of Michigan. He was the recipient of a 2012 Presidential Early Career Award for Scientists and Engineers (PECASE) for his research in trapped ion quantum computing.

ABSTRACT

We present a new method for coherent control of trapped ion qubits in separate interaction regions of a multizone trap by simultaneously applying an electric field and a spin-dependent gradient. Both the phase and amplitude of the effective single-qubit rotation depend on the electric field, which can be localized to each zone. We demonstrate this interaction on a single ion using both laser-based and magnetic-field gradients in a surface-electrode ion trap, and measure the localization of the electric field.

ABSTRACT

Exploring Ion Trap Scaling and Integrated Photonics for QCCD Architecture

The quantum charge-coupled device (QCCD) architecture allows trapped ion systems to scale up to large number of qubits while maintaining high-fidelity operations.  Incorporated into Quantinuum’s recently released H2 commercial quantum computer are several scalable features such as electrode broadcasting, multi-layer RF routing, and magneto-optical trap loading.  In addition, transport of ions through multiple junctions have been demonstrated on multiple Quantinuum traps.  In this talk, I will discuss these key technology demonstrations on our roadmap to scaling, as well as some recent progress in integrated photonics.

BIO

Patty Lee is the Chief Scientist for hardware technology development for commercial trapped ion quantum computers at Quantinuum.  She received her PhD from University of Michigan in Ann Arbor, where her thesis research advanced the understanding of phase control for geometric phase gates in trapped ions.  She has worked as an experimental physicist at NIST Gaithersburg, US Army Research Laboratory (ARL), and Lockheed Martin. She joined Honeywell Quantum Solutions in 2016, where her work focused on developing the quantum charge-coupled device (QCCD) architecture for commercial trapped ion quantum computers.  In 2021, Honeywell Quantum Solutions and Cambridge Quantum Computing combined to form Quantinuum, and she continues to drive technology innovations that lead to high performance quantum computers and pave the way for fault-tolerance.

ABSTRACT

In this presentation, I will discuss efforts in the quantum community and at IonQ to develop chip-scale technology to enable higher-performance and more scalable trapped-ion quantum computer systems. The presentation will focus on the benefits and challenges of using this technology today and in the future, and on approaches to ensure successful integration of new quantum technology into commercial quantum computer systems.

BIO

Dr. Jeremy Sage is the Director of Integrated Devices at IonQ. His work focuses on the development and production of chip-scale technology, including ion traps and photonic integrated circuits (PICs, for high-performance and scalable trapped-ion quantum computer systems. Before joining IonQ, Dr. Sage was a Senior Staff member at MIT Lincoln Laboratory and a Principal Investigator in MIT’s Center for Quantum Engineering (CQE), where he co-led a research group focused on developing technology and techniques for trapped-ion quantum computing and sensing. Dr. Sage received a  Ph.D. in Physics from Yale University and a B.Sc. in Math/Physics from Brown University.

ABSTRACT

Making use of superposition and entanglement, it is possible to build quantum computers that can solve certain problems, that would require millions of years of computing time on even the fastest supercomputer. Such problems include drug discovery and simulation of chemical reactions, making aircraft engines more fuel efficient, optimisation problems, breaking encryption, quantum machine learning, simulation of other quantum systems but really span across nearly any industry sector.

Current quantum computers can only operate with around 100 quantum bits while most disruptive industry applications would require quantum computers that can process millions of quantum bits.  I will discuss a recent achievement, the demonstration of electric fields links between ion microchips as well as successful transport of ion qubits between microchips that should enable the construction of quantum computers with millions of quantum bits. I report the demonstration of a quantum matter-link in which ion qubits are transferred between adjacent quantum computer modules [1]. Ion transport between adjacent modules is realised at a rate of 2424 s⁻¹ and with an infidelity associated with ion loss during transport below 7 × 10⁻⁸. Furthermore, I will show that the link does not measurably impact the phase coherence of the qubit. I will also discuss the path forward to build practical trapped ion quantum computers. This includes the underlying research within our research group at the University of Sussex; an engineering focussed approach to construct practical machines at spin-out company Universal Quantum; work with future quantum computing users to develop applications and use cases in order to fast track the demonstration of disruptive industry applications. [1] A High-Fidelity Quantum Matter-Link Between Ion-Trap Microchip Modules, M. Akhtar, F. Bonus, F. R. Lebrun-Gallagher, N. I. Johnson, M. Siegele-Brown, S. Hong, S. J. Hile, S. A. Kulmiya, S. Weidt & W. K. Hensinger, A high-fidelity quantum matter-link between ion-trap microchip modules. Nature Communications 14, 531 (2023)

BIO

Prof Winfried Hensinger is a Professor of Quantum Technologies at the University of Sussex. He heads the Sussex Ion Quantum Technology Group and he is the director of the Sussex Centre for Quantum Technologies. Hensinger’s group is working on developing practical trapped-ion quantum computers. In 2016, Hensinger and his group invented a new approach to quantum computing with trapped ions where voltages applied to a quantum computer microchip are used to execute calculations instead of laser beams as in previous approaches. In 2017, leading an international consortium, he announced the first industrial blueprint for building a practical quantum computer with millions of qubits (https://bit.ly/3tCug5O) giving rise to the assertion that is now possible to construct a utility scale quantum computer making use of microwave technology. He is a co-founder of Universal Quantum, a full stack quantum computing company, where he serves as Chief Scientist and Chairman. Hensinger is also an honorary professor at the University of Bristol and he serves on EPSRS’s Physical Sciences Strategic Advisory Team.

ABSTRACT

The strontium ion shows promising potential as an ideal candidate for medium-distance quantum networking due to its atomic transition at 1092 nm. Depending on the specific communication mode and fiber loss characteristics, this transition could align well with pre-existing fiber optic infrastructure. Consequently, the need for lossy photon conversion processes is eliminated, facilitating direct remote entanglement at kilometer scales. In our experimental setup, we generated 1092 nm photons and conducted measurements of the parity operator and correlation measurements between the ion and photon under different bases. These preliminary findings represent a significant step towards realizing ion-photon entanglement at near-telecom wavelengths,  our research and optimization will be crucial in fully harnessing their potential for real-world quantum communication. 

BIO
Yuanheng Xie is a dedicated quantum physicist, with a keen focus on exploring applications of trapped ion systems. He received his undergraduate degree from the University of Science and Technology and completed his doctoral degree in Atomic Physics at Indiana University. Currently, a postdoctoral researcher at Duke University with Prof. Norbert Linke’s group, Yuanheng’s research interests encompass quantum simulation and quantum networking. He is passionately driven to delve into quantum many-body physics and harness the potential of trapped ion systems as a powerful resource for quantum information processing. 

ABSTRACT

In recent years, the integration of optical components with trap devices is emerging as a strong and growing tool for scaling quantum technologies based on trapped ions.

In my contribution, I will discuss the potential role of integrated optics in scaling trapped ion devices, and illustrate the current state of the art through the most recent applications. Several experimental demonstrations have highlighted the potential behind integrated optics, leading to control and on-chip delivery of multiple wavelengths of laser light [1], quantum control of multiple ions [2], and generation of engineered laser fields for addressing particles with structured light [3, 4].

In particular, integrated optics bring into the game a new element of modularity, which naturally finds its application in architectures that take advantage of distributing computational power in multiple interconnected trap zones. The desired configuration of laser beams can be reproduced efficiently across the device, without optical access limitations, allowing to scalably implement coherent operations distributed across trap zones, connected by ion transport [5].

Finally, I would give an overview of the upcoming innovations – new materials, trap architectures, optical design – and the associated challenges. [1] R. Niffenegger et al., Nature 586, 538–542 (2020) [2] K. Mehta et al., Nature 586, 533-537 (2020) [3] G. Beck at al., arxiv:2306.09220 (2023) [4] A. Ricci et al., Phys. Rev. Lett. 130, 133201 (2023) [5] C. Mordini et al., in preparation.

BIO

During my doctoral studies at the BEC Center in Trento, I worked on Bose-Einstein condensates in ultracold atomic samples, building a strong expertise on experimental atomic physics as well as a theoretical understanding on fundamental many-body physics.

I leaded a project on an experimental measure of thermodynamic properties of a single species, three-dimensional condensate of weakly interacting atoms, developing a novel single-shot imaging technique for highly dense atomic samples, which allowed the first measurement of the canonical equation of state of this quantum gas.

Furthermore, I participated in the construction of a new experimental apparatus dedicated to spin mixtures of BECs, where I collaborated on several projects related to superfluidity of spinor condensates and the dynamics of their solitonic excitations. At my second postdoc in the group of Trapped Ions Quantum Information at ETH, I specialized in ion trapping in a novel type of surface electrode traps with integrated photonics. We investigate the use of this promising combination of technologies as a tool for implementing scalable computing platforms, and for manipulating atom-light interactions via engineered laser fields. Furthermore, I supervise a number of projects related to ion transport and manipulation of ion crystals in both surface-electrode and 3D traps.