USTC IonQNet Group

High optical access (HOA) trap

2026-10-03T00:00:00+08:00

Four directions of high-NA optical access

Our high-optical-access apparatus (Review of Scientific Instruments, 2021) places a miniaturized blade-electrode ion trap in an all-glass cell, opening optical paths for tightly focused control beams and fluorescence collection. The geometry supports high-numerical-aperture objectives from four directions. These objectives provide multi-directional addressing, ion imaging and quantum-state readout, allowing the optical system to be configured around the needs of each experiment.

From precise addressing to new quantum gates

The HOA platform supports our research on ion control with tightly focused light and optical tweezers. We used its optical access to develop low-crosstalk dual-sided Raman addressing, then used the optical Magnus effect to implement addressed entangling gates with single-sided polarization-gradient control. Together with in-situ aberration correction using an ion probe, high-quality focused fields allow us to select individual qubits and couple to axial motion along an ion chain.

Optical control of the crystal’s motional spectrum

The open optical geometry also allows local optical-tweezer potentials to be combined with electrical confinement. We have demonstrated optical control of an ion’s vibrational frequency and are investigating how local light fields can dynamically reshape the frequencies and spatial structure of phonon modes in a crystal. This approach aims to reduce crosstalk from unwanted motional modes and provide additional control for high-fidelity gates directly within ion crystals.

Explore our trapped-ion quantum computing research →

Optical-tweezer ion gates

2026-10-03T00:00:00+08:00

Addressed gates with the optical Magnus effect

Tightly focused light provides more than a small addressing spot: its spatially varying polarization offers a new way to couple an ion’s spin to its motion. Using the optical Magnus effect, we implemented addressed entangling gates driven by co-propagating Raman light through a single objective. This geometry simplifies the optical interface while retaining flexible selection of the ions involved in the gate.

The work was reported in Physical Review Letters 135, 260604 (2025). After correcting for state-preparation and measurement errors, the measured Bell-state fidelities were 98.7(1)% in a two-ion chain and 97.2(4)% in a four-ion chain.

From precise addressing to phonon control

We combine single-sided polarization-gradient control with in-situ aberration correction and coupling to axial motional modes. Optical tweezers also provide local potentials for tuning ion motion; building on demonstrated control of an ion’s vibrational frequency, we are developing ways to reshape phonon modes within ion crystals and reduce unwanted motional crosstalk.

Explore the trapped-ion quantum computing research →

See the high optical access (HOA) trap →

Yun-Feng Huang

2026-04-01T10:00:00+08:00

Profile

Yun-Feng Huang is a Researcher in the Department of Optics and Optical Engineering at the University of Science and Technology of China. His research interests include quantum communication, photonic quantum information processing, and trapped-ion quantum information processing.

Education

1998-2003, Ph.D. program, Department of Physics, University of Science and Technology of China
1994-1998, B.S., Department of Physics, University of Science and Technology of China

Experience

2009-present, Researcher, Department of Optics and Optical Engineering, University of Science and Technology of China
2006-2008, Associate Professor, Department of Physics, University of Science and Technology of China
2003-2005, Lecturer, Department of Physics, University of Science and Technology of China

Research

Current work focuses on building quantum networks based on trapped-ion systems, including enhanced trapped-ion nodes, photonic quantum channels and hybrid quantum networks. His group has carried out experimental studies with Yb and Ba ions confined in linear ion traps.

Chen-Xu Wang

2026-03-31T20:20:00+08:00

Education

2021.9-now, University of Science and Technology of China, Department of Optics and Optical Engineering, Doctor
2017.8-2021.6, Ocean University of China, Faculty of Information Science and Engineering, Bachelor

Research

Quantum information with trapped ions. Quantum simulation, quantum network, distributed quantum computation.

Quantum Interface Concept

2026-03-28T10:23:00+08:00

Quantum interfaces connect stationary matter qubits to photons that carry quantum information between remote nodes. In our research, trapped ions provide coherent local processing, while cavity interfaces and frequency conversion connect those processors to optical channels and other quantum systems.

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Hybrid Quantum Network

2026-03-28T10:21:00+08:00

Trapped ions provide long-lived coherence and high-fidelity quantum operations, while solid-state memories store photonic quantum states. We develop interfaces that combine these capabilities in a hybrid network, connecting local ion control with remote optical storage.

Our polarization-preserving frequency converter bridges the 369.5 nm emission of a ytterbium ion and the 580 nm transition of a europium-doped crystal memory. A Sagnac loop stabilizes the polarization components, and off-axis parabolic mirrors provide achromatic coupling across the wavelength bands (Chinese Optics Letters, 2026). The two figures show the network architecture and the experimental system linking the ion node, frequency converter and memory.

Working with Professor Zong-Quan Zhou’s team, we established ion–memory entanglement between laboratories separated by 75 m and connected by 90 m of optical fiber. Joint measurements after storage and retrieval verify quantum correlations across this heterogeneous link. The experiment is reported in the preprint Heterogeneous entanglement between a trapped ion and a solid-state quantum memory (arXiv:2603.05836), with further details in Chen-Xu Wang’s doctoral thesis (2026). We plan to extend these interfaces to neutral-atom systems and explore distributed quantum computing across physical platforms.

Explore our hybrid quantum network research →

Cavity QED Interface

2026-03-28T10:20:00+08:00

We integrate fiber microcavities with needle ion traps to develop ion–photon interfaces for quantum networks. The small cavity mode volume enhances ion–cavity coupling, while the fibers provide channels for collecting and transmitting photons. By designing the mirrors, trapping geometry and optical coupling together, we aim to build network nodes that combine high bandwidth with high efficiency.

The photographs show the hardware behind this interface. Gold coating on the fiber sides and the outer regions of the end faces provides electrical shielding while leaving the central optical apertures open. Two opposing fiber mirrors form a microcavity, which is integrated with the needle trap inside the vacuum chamber. The fluorescence image of a single Ba⁺ ion between the mirrors shows the ion confined within this cavity geometry.

Explore quantum networking with cavity QED →

"Transverse Polarization Gradient Entangling Gates for Trapped-Ion Quantum Computation" is published in Physical Review Letters

2025-12-25T10:00:00+08:00

Our work “Transverse Polarization Gradient Entangling Gates for Trapped-Ion Quantum Computation” has been published in Physical Review Letters as an Editors’ Suggestion on December 24, 2025.

We realized high-fidelity entangling gates for trapped ions based on the polarization gradient of tightly focused light. This scheme simplifies the current entangling gate configuration and is compatible with the optical tweezer architecture, holding great significance for large-scale trapped-ion quantum computation.

Background and Challenge

Trapped-ion quantum systems, with their ultra-high operation fidelity and coherence, are one of the leading physical platforms for building large-scale quantum computers. Ion-array-based quantum computing architectures, which construct quantum processors through optically addressing individual ion qubits in parallel, offer the advantages of high connectivity and parallel computational efficiency. However, scaling up this architecture faces a fundamental challenge: dense phonon modes in large ion arrays cause gate crosstalk, making it difficult to implement high-fidelity entangling gates directly. In recent years, the international community has proposed using tightly focused optical tweezer arrays to reshape the ion phonon spectrum and suppress crosstalk, but demonstrating optical tweezer gates in optically addressed ion-trap quantum computers has not yet achieved a breakthrough.

The Optical Magnus Effect Approach

Building on years of innovative research and independent development in trapped-ion quantum computation, our team has realized a novel entangling gate scheme based on the optical Magnus effect: analogous to the Magnus effect in fluid dynamics, a spinning ion in a focused light stream (optical tweezer) experiences a transverse force — perpendicular to the light propagation direction. This scheme exploits the transverse field gradient of a tightly focused laser to create a state-dependent push that establishes quantum entanglement between ions. This approach eliminates the traditional complex counter-propagating laser beam configuration, greatly simplifying the experimental setup and reducing operational complexity.

Key Results

After correcting for state-preparation and measurement errors, we measured Bell-state fidelities of 98.7(1)% in a two-ion chain and 97.2(4)% in a four-ion chain of ¹⁷¹Yb⁺ ions. This quantum gate is capable of achieving fidelities above 99.99% in theory. We analyzed and discussed the main sources of infidelity in the current experiment, and expect to reduce the gate error by more than an order of magnitude in future experiments.

Fig. 1. Principle of polarization-gradient-based individual addressing. An acousto-optic deflector (AOD) generates multiple laser spots through a high-NA objective lens, producing polarization gradients that enable spin-dependent forces on individual ions.

Significance

The key innovation of this technique lies in its excellent compatibility with optical tweezer gates — since the tweezer operation itself involves transverse motion — and the significant simplification of optical configurations, making the optical tweezer gate scheme highly feasible in experiment. This provides a simpler and more flexible path toward large-scale, scalable trapped-ion quantum computation.

Reviewers gave high praise: “This paper demonstrates a successful combination of optical tweezers with linear ion chains, proposing an ingenious and powerful mechanism through which two-qubit gate operations can be realized between arbitrary ion pairs…” and “The results of realizing this type of quantum gate are encouraging, and this method addresses an important challenge in scaling up ion-trap quantum computation…”

Find the article here: https://doi.org/10.1103/w5l6-wmrl

See also the report by Photon Box (光子盒): https://news.qq.com/rain/a/20251225A06IAR00

(Source: China Science Daily, by Min Wang)

"A neural network assisted ¹⁷¹Yb⁺ quantum magnetometer" is published in npj Quantum Information

2022-12-22T10:00:00+08:00

Our work “A neural network assisted ¹⁷¹Yb⁺ quantum magnetometer” has been published in npj Quantum Information. We demonstrate the power of combining machine learning with quantum sensing by integrating neural networks into the data processing stage of a trapped-ion magnetometer, significantly extending its operational regime.

The Challenge

A versatile quantum magnetometer must deliver a readable response across a wide range of target field parameters. Standard atomic magnetometers operate in a regime leading to harmonic sensor responses, where RF target parameters are encoded in simple sinusoidal patterns. However, when the RF driving induces responses beyond this standard harmonic behavior — for instance, with large shot noise or in continuous single-shot measurement scenarios — the simple relationship between sensor responses and target parameters breaks down, making accurate field characterization extremely challenging.

Our Approach

We experimentally demonstrated that combining ¹⁷¹Yb⁺ atomic sensors with adequately trained neural networks enables us to investigate target fields in distinct challenging scenarios. Specifically, we characterized radio frequency (RF) fields in the presence of large shot noise, including the limit case of continuous data acquisition via single-shot measurements. The neural network learns the complex mapping between measured sensor responses and the underlying field parameters, effectively deciphering the information contained in non-trivial sensor responses.

Key Results

In the scenario of reduced measurement averaging, our neural network achieved an average estimation accuracy of 98.76% with only 100 measurement shots per data point. Even with as few as 30 shots, the accuracy remained at 98.31%. For continuous single-shot measurements, the regression between NN outputs and targets showed correlation coefficients exceeding R = 0.999. These results demonstrate that the hybridization of machine learning tools with quantum sensing techniques is a strategy that can be readily extended to other quantum platforms, such as nitrogen-vacancy centers in diamond.

Fig. 1. Energy levels of the ¹⁷¹Yb⁺ atomic sensor (a, b), the needle trap configuration (c), and the neural network architecture (d). The sensor response from the photomultiplier tube (PMT) is processed through a well-trained neural network to extract RF field parameters from complex sensor responses.

This work was a collaboration with researchers from the University of the Basque Country (UPV/EHU) in Spain.

Find the article here: https://doi.org/10.1038/s41534-022-00669-2

"Super-resolved Imaging of a Single Cold Atom on a Nanosecond Timescale" is published in Physical Review Letters

2021-12-24T10:00:00+08:00

Our work “Super-resolved Imaging of a Single Cold Atom on a Nanosecond Timescale” has been published in Physical Review Letters. We demonstrate a groundbreaking method to image a single trapped ion with unprecedented spatial and temporal resolution, breaking through the optical diffraction limit.

Breaking the Diffraction Limit

High-resolution optical detection and imaging of individual particles in cold atomic systems is essential for directly probing quantum phenomena such as transport, correlations, and phase transitions. However, traditional microscopy techniques are fundamentally restricted by the wavelength-scale diffraction limit, making them unsuitable for studying wave function details of many-body systems. We brought the concept of super-resolved microscopy — which has matured as a powerful tool in biology and chemistry — into the realm of cold atoms.

Our Method: Ground-State Depletion Microscopy

We demonstrated ground-state depletion (GSD) microscopy on a trapped-ion system for the first time. By combining the GSD control sequence with the qubit-state polarization and detection methods of ¹⁷¹Yb⁺ ions, we achieved 2D super-resolved imaging beyond the optical diffraction limit. The key innovation is using a high-purity doughnut-shaped laser beam, generated via a digital micromirror device (DMD) with in-situ aberration correction, to selectively deplete the ion’s quantum state.

Results

We achieved a spatial resolution of 175 nm using a NA = 0.1 imaging objective — a 13-fold improvement compared with direct fluorescence imaging. Moreover, the depletion process can be as short as ~50 ns under strong laser power, enabling us to take stroboscopic images on nanosecond timescales. We demonstrated this capability by observing one complete cycle of the ion’s secular motion within 735 ns, achieving a displacement detection sensitivity of 10 nm.

Fig. 1. Experimental scheme and setup. (a) Energy levels of ¹⁷¹Yb⁺ and the three-laser GSD imaging sequence. (b) A Paul trap with the doughnut beam focused through the top window. (c) Schematic of the super-resolved imaging process: scanning the doughnut spot pixel by pixel to build a super-resolved image.

Our method provides a powerful tool for probing particle positions, momenta, correlations, and dynamics in cold atomic systems, and can be readily extended to neutral atoms in optical tweezers.

Find the article here: https://doi.org/10.1103/PhysRevLett.127.263603

"Riemann zeros from Floquet engineering a trapped-ion qubit" is published in npj Quantum Information

2021-07-01T10:00:00+08:00

Our work “Riemann zeros from Floquet engineering a trapped-ion qubit” was published in npj Quantum Information on July 14, 2021. This work bridges quantum physics and number theory by experimentally measuring the zeros of the Riemann zeta function using a trapped-ion quantum system.

Background

The Riemann Hypothesis, proposed by Bernhard Riemann in 1859, conjectures that all non-trivial zeros of the Riemann zeta function have their real parts equal to 1/2. As one of the seven Millennium Prize Problems, its proof would profoundly advance our understanding of prime number distribution. An intriguing approach to this problem is the Hilbert-Pólya conjecture, which proposes the existence of a quantum system whose Hamiltonian eigenvalues correspond one-to-one with the Riemann zeros.

Our Approach

We proposed, for the first time internationally, a quasi-static Hamiltonian method. By designing a periodic driving function to modulate a trapped-ion qubit, we realized quasi-static evolution of the quantum state. When the driving parameter corresponds to a Riemann zero, the engineered quasienergies become degenerate and the quantum state remains frozen at integer multiples of the driving period — a phenomenon known as coherent destruction of tunneling. This is described by Floquet theory, where the quasienergies of the periodically driven system are regulated by the driving parameters. By scanning over the driving amplitude, the locations of the Riemann zeros can be measured to a high degree of accuracy.

Results

Using our self-developed trapped-ion system with long coherence times, we implemented 30-period high-fidelity driving and successfully measured the first 80 non-trivial Riemann zeros — improving upon previous work in this field by nearly two orders of magnitude. Our experimental results provide important evidence for studying the Hilbert-Pólya conjecture and deepening the connection between the Riemann Hypothesis and quantum systems.

Reviewers commented: “I am recommending publication, for several reasons: the high level of experimental ingenuity required to make the scheme work; the clear description of theory and experiment; and the large numbers and high accuracy of the measured zeros.”

Fig. 1. Experimental procedure to measure Floquet dynamics in a trapped-ion system. (a) The qubit is periodically driven by a microwave field generated by an AWG. (b) On the Bloch sphere, the qubit is initialized to |0⟩ and evolves to U(nT)|0⟩ after n periods of driving, with the freezing of dynamics revealing the Riemann zeros.

The first author of this paper is Dr. Ran He from our laboratory. This work was supported by the Ministry of Science and Technology, NSFC, CAS, and Anhui Province.

Find the article here: https://doi.org/10.1038/s41534-021-00446-7

"Quantum thermodynamics in adiabatic open systems and its trapped-ion experimental realization" is published in npj Quantum Information

2020-09-18T10:00:00+08:00

Our work “Quantum thermodynamics in adiabatic open systems and its trapped-ion experimental realization” has been published in npj Quantum Information. In collaboration with our Brazilian colleagues, we established general formulas for quantum thermodynamics in adiabatic open systems, bridging quantum adiabatic processes and thermodynamic adiabatic processes, and verified our theory experimentally using trapped ions.

Motivation

Thermodynamics, built upon macroscopic observations of matter, has achieved tremendous success across many systems. With the development of quantum technology enabling precise preparation and control of quantum systems, a fundamental question emerges: do the laws of thermodynamics still apply at the quantum scale? Quantum thermodynamics has thus gradually developed, aiming to study the emergence and limits of thermodynamic laws from the microscopic perspective of quantum mechanics, addressing long-standing puzzles such as Maxwell’s demon.

Key Contributions

Quantum adiabatic processes and thermodynamic adiabatic processes are fundamental components of quantum theory and thermodynamics, respectively. Exploring the relationship between them is a fascinating and complex problem. We derived general formulas for heat, work, internal energy, and entropy in open quantum systems, and established that quantum mechanical adiabaticity and thermodynamic adiabaticity are generally not equivalent — thermal adiabaticity requires a sufficient condition satisfied by quantum systems adiabatically evolving under a steady-state trajectory.

Experimental Verification

We implemented the experiment using our trapped-ion system. The trapped ion offers long coherence times, multiple controllable degrees of freedom (spin and motion), and serves as an ideal platform for quantum information processing. We developed an innovative solution to simulate time-dependent decoherence channels by using noise-modulated carrier frequency, achieving a fidelity of over 99.5% in simulating the quantum decoherence channel. This enabled us to analyze heat and internal energy in a fully controllable dynamical process with high-fidelity quantum state manipulation.

Fig. 1. Experimental scheme to investigate the thermodynamics of adiabaticity in open quantum systems. (a) Schematic of the six-needle Paul trap and relevant energy levels. (b) Experimental microwave instrument for generating the driving field and controlling the Gaussian noise as a dephasing channel.

Reviewers gave high praise: “The present work would be one of the very few, and probably the most convincing, theoretical and experimental discussion on the relation between thermodynamical adiabatic processes and quantum adiabatic processes in open quantum systems.”

The first author is Dr. Chang-Kang Hu, a former PhD student from our laboratory. This work was supported by MOST, NSFC, CAS, Anhui Province, and the Postdoctoral Science Fund.

Find the article here: https://doi.org/10.1038/s41534-020-00300-2

"Experimentally testing quantum critical dynamics beyond the Kibble-Zurek mechanism" is published in Communications Physics

2020-02-14T10:00:00+08:00

Our work “Experimentally testing quantum critical dynamics beyond the Kibble-Zurek mechanism” has been published in Communications Physics (Nature). Building on our earlier Kibble-Zurek experiment, we go beyond the standard KZM to probe the full probability distribution of topological defects formed during a quantum phase transition.

Beyond the Mean: Full Counting Statistics

The Kibble-Zurek mechanism (KZM) describes the universal dynamics across a phase transition, predicting that the average number of topological defects scales as a universal power law with the quench rate. However, the KZM focuses only on the mean number of defects. In this work, we aim to validate a much richer prediction: the measured distribution of kink pairs follows a Poisson binomial distribution, in which all low-order cumulants scale with universal power laws.

Quantum Simulation in Momentum Space

We experimentally probed the distribution of kink pairs in a one-dimensional quantum Ising chain driven across the paramagnet-ferromagnet quantum phase transition, using a single ¹⁷¹Yb⁺ trapped ion as a quantum simulator in momentum space. Each mode of the quantum Ising model is mapped to a Landau-Zener crossing, whose dynamics can be simulated with our ion-trap qubit. By measuring the excitation probability for each mode, we reconstruct the full counting statistics of topological defects.

Key Results

We experimentally verified the universal scaling of the first cumulants and reported deviations due to noise-induced dephasing of the trapped ion. Our results establish that the universal character of critical dynamics extends beyond KZM, from the mean kink number to the full probability distribution of topological defects — providing a much more stringent test of universality at quantum phase transitions.

Fig. 1. Experimental setup. (a) A single ¹⁷¹Yb⁺ ion trapped in a needle trap. (b) The qubit energy levels. (c) The qubit is driven by a microwave field, with operations programmed via an arbitrary waveform generator (AWG).

This work was done in collaboration with Fernando Javier Gómez-Ruiz and Adolfo del Campo from the Donostia International Physics Center, Spain.

Find the article here: https://doi.org/10.1038/s42005-020-0306-6

"Experimental demonstration of suppressing residual geometric dephasing" is published in Science Bulletin

2019-09-20T10:00:00+08:00

Our work “Experimental demonstration of suppressing residual geometric dephasing” has been published in Science Bulletin. We experimentally demonstrate effective suppression of residual geometric dephasing — a key obstacle for high-fidelity geometric quantum gates — using modified dynamical decoupling schemes on a single trapped ¹⁷¹Yb⁺ ion.

The Problem: Residual Geometric Dephasing

The geometric phase (Berry phase) is a promising strategy for fault-tolerant quantum information processing because it depends only on the geometry of the path executed, not the dynamics. However, decoherence caused by environmental noise destroys the geometric phase. Traditional dynamical decoupling sequences such as Spin Echo (SE) and CPMG can eliminate dynamic dephasing but cannot reduce residual geometric dephasing, which remains a critical barrier for high-precision geometric quantum manipulation.

Our Solution

We designed modified dynamical decoupling schemes that carefully choose the angles of neighboring adiabatic paths on the Bloch sphere. By varying the tilt angles in the SE and CPMG sequences, we ensure that the accumulated geometric dephasing in successive segments cancels out. This is achieved through two schemes:

Modified SE: Using different slant angles for neighboring evolution segments so that the geometric dephasing contributions cancel.
Modified CPMG: Separating adiabatic paths into four parts with swapping π pulses, ensuring zero net geometric dephasing.

Results

Our experimental results demonstrate that the modified schemes can reduce the dephasing rate by more than one order of magnitude compared with traditional dynamical decoupling schemes in the regime where residual geometric dephasing dominates. We also investigated the impact of noise intensity and correlation time on the coherence of the quantum system, confirming that these methods are effective across a wide range of noise conditions.

Fig. 1. Dynamics of Hamiltonian H in the Bloch sphere and corresponding geometric phase. (a) The Hamiltonian H tilted by angle θ evolves around the z axis, accumulating both dynamic and geometric phases. (b) The spin echo strategy, where the Hamiltonian rotates in opposite directions, eliminates dynamic phase and acquires pure geometric phase.

Find the article here: https://doi.org/10.1016/j.scib.2019.09.007

Mingzhong Ai

2018-05-09T00:00:00+08:00

Personal data

Address: Key Laboratory of Quantum Information, CAS, USTC, Jinzhai Road #96, Hefei, Anhui, P. R. China, 230026
Phone: (+86) 18214880012
E-mail: amz@mail.ustc.edu.cn

Education

Ph.D. (enrolled September 2016), Key Lab of Quantum Information, Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui, China
2012.9-2016.7 B.Sc., Department of Physics, Shandong University, Jinan, Shandong, China

"An Ultraviolet Fiber Fabry–Pérot Cavity for Florescence Collection of Trapped Ions" is published

2017-01-22T10:20:00+08:00

Our work “An Ultraviolet Fiber Fabry–Pérot Cavity for Florescence Collection of Trapped Ions” has been published in Chinese Physics Letters. We demonstrate a fiber Fabry–Pérot cavity (FFPC) operating in the ultraviolet range at 369 nm, specifically designed for enhancing fluorescence collection from trapped ¹⁷¹Yb⁺ ions — a key technology for building scalable quantum networks.

Why Fiber Cavities?

Trapped ions are an ideal platform for quantum information processing, but building a large-scale quantum computer and long-distance quantum communication requires the ability to remotely distribute entanglement between ions. The key ingredient is efficient photon collection. A fiber Fabry–Pérot cavity can provide a large Purcell factor to enhance the photon emission rate while maintaining high coupling efficiency between the single fiber mode and the cavity mode — solving the long-standing problem of low photon collection efficiency.

Technical Achievements

We designed the FFPC at the bad cavity limit for fluorescence enhancement at the ²P_1/2 to ²S_1/2 transition wavelength of Yb⁺. The concave mirror profiles on fiber-end faces were fabricated using CO₂ laser machining with spatial filtering, achieving an averaged eccentricity of only 0.22 ± 0.04. The mirrors were coated for high reflection in the ultraviolet range by ion-beam sputtering, achieving a coating reflectivity of 99.76% and a finesse of 1300 ± 100.

Key Results

Based on measured experimental parameters and numerical simulation, we estimate:

Purcell factor > 2.5
Single-mode fiber collection efficiency > 10%

These results demonstrate the FFPC’s potential to entangle remote ions, which is the basis for constructing quantum networks and developing distributed quantum computation.

Fig. 1. Schematic diagram of the laser machining setup for fabricating FFPCs, and surface characterization of the machined fiber-end face using AFM. The setup uses a CO₂ laser with spatial filtering to produce concave mirror profiles with high circularity.

Find the article here: https://doi.org/10.1088/0256-307X/34/1/013701

"Experimental Trapped-ion Quantum Simulation of the Kibble-Zurek dynamics in momentum space" is published

2016-09-22T10:20:00+08:00

Our work Experimental Trapped-ion Quantum Simulation of the Kibble-Zurek dynamics in momentum space was published in Scientific Reports. This was our group’s first trapped-ion experiment, following the development of the platform that began in 2013. We thank our collaborators Le Luo and Adolfo del Campo for their contributions to the experiment and theory.

Simulating a quantum phase transition

The Kibble–Zurek mechanism predicts how defects form when a system is driven through a continuous phase transition. Testing this scaling in a quantum system requires controlled state preparation, tunable dynamics and accurate measurements of the resulting excitations.

We used a single trapped ion to simulate a transverse-field Ising chain in momentum space. Each momentum mode is represented by a two-level system, allowing its excitation probability to be measured separately. Combining these measurements reconstructs the defect density of the simulated chain.

The experiment observed the predicted power-law scaling as the system crossed the quantum critical point at different rates, providing an experimental test of the Kibble–Zurek mechanism in the quantum regime.

Fig. 1. Experimental platform: the six-needle ion trap, the hyperfine levels used as a qubit, and the microwave control system that drives the simulated dynamics.

Paper link: Scientific Reports 6, 33381 (2016)

Ran He

2016-09-21T10:20:00+08:00

PhD alumnus
office:316
email:heran@mail.ustc.edu.cn

Introduction:

I received my bachelor’s degree from Dalian University of Technology (DUT). During a summer visit to USTC, I became interested in trapping single ions and manipulating their quantum states with lasers, and subsequently joined the ion-trap group as a PhD student. My doctoral research focused on developing ion traps for confining multiple ions and addressing them individually.

In 2017.11 to 2018.11, I visited Jonathan’s ion trap group (TIQI) at ETH, Zurich as an academic guest.

Chang-Kang Hu

2016-09-19T10:20:00+08:00

Jin-Ming Cui

2016-09-19T10:20:00+08:00

Personal Information

Education

2008.9-2013.6, University of Science and Technology of China, Department of Optics and Optical Engineering, Doctor
2004.8-2008.6, University of Science and Technology of China, Department of Physics, Bachelor

Research

Quantum information with trapped ions. Quantum simulation, cavity QED, quantum network, distributed quantum computation.

Wei-Min Lv

2016-09-19T10:20:00+08:00

Education

2013.9-2016.6, University of Science and Technology of China, Department of Optics and Optical Engineering, PhD
2009.8-2013.6, Hefei University of Technology, School of Instrument Science and Opto-electronic Engineering, Bachelor

Contact

Tel: +86 13866664268
Email: weimin@mail.ustc.edu.cn
Address: Key Laboratory of Quantum Information, CAS, USTC, 96 Jinzhai Road, Hefei, Anhui 230026, China