Quantum AI Research Tracker

Quantum Machine Learning
& Hybrid Quantum-Classical AI

Curated index of papers, architectures, and advances at the intersection of quantum computing, deep learning, LLMs, and vision - covering fully quantum networks and hybrid quantum-classical models.

25+Key Papers
8Topics Covered
2019–26Time Span
5+HW Platforms
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Latest & Highlighted

Most recent results and breakthrough papers - click any card to read the full analysis with equations and architecture diagrams.

2024 Vision Hybrid Q-C
Quantum Vision Transformers KEY
Cherrat, Kerenidis, Mathur et al.

Orthogonal quantum layers via RBS gates replace classical linear layers in ViT. Achieves competitive accuracy with provably quantum advantage in inference scaling.

Read analysis → equations + architecture
2024–25 Theory
Barren Plateaus via Dynamical Lie Algebras THEORY
Ragone & Larocca (2024); Cerezo et al. (2025)

Unifies barren plateau theory via DLA dimension. $\text{Var}[\partial_\mu E] \leq C / |\mathfrak{g}|$ — exponential in $n$ for generic circuits.

Read analysis → DLA theory + mitigation
2024 NLP/LLM Hybrid Q-C
Quixer · HyQuT · QTHA KEY
Nguyen et al.; Chen et al.

Quantum transformer architectures for language: full quantum self-attention, hybrid Q/K/V decomposition, and token-level hybrid attention.

Read analysis → architectures + circuits
2024 Generative Hybrid Q-C
QuDDPM · MSQuDDPM
Cacioppo et al.; Various

Quantum score network replaces classical U-Net in DDPM. Decoherence channels as natural quantum noise schedule. Multi-scale extension.

Read analysis → forward/reverse process
2009–23 Algorithms
HHL & QSVT: Quantum Linear Algebra
Harrow, Hassidim, Lloyd; Gilyén et al.

Exponential speedup for linear systems via phase estimation. QSVT unifies quantum algorithms via block-encoding + quantum signal processing.

Read analysis → circuit complexity
2024 News Hardware
Google Willow: Below-Threshold QEC
Google Quantum AI — December 2024

First demonstration of below-threshold quantum error correction. Error rate decreases exponentially as code distance increases. 105 physical qubits; RCS benchmark: $10^{25}\times$ classical.

arXiv →
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Chronological Timeline

Filter:
2026
2026 Hybrid Q-C
Quantum-Classical Co-Design for Hybrid Inference
Various — preprint 2026
Co-designed quantum-classical pipelines for efficient inference on near-term devices; explores which layers benefit from quantum acceleration.
2026 Theory Hardware
Fault-Tolerant QML: LDPC Codes & Logical Qubits
Various — ongoing work
Early fault-tolerant quantum ML using LDPC codes, targeting logical qubit counts achievable on near-term hardware.
2025
Nov 2025 NLP/LLM Hybrid Q-C
HyQuT: Hybrid Quantum Transformer for Language Generation
Kong et al. — arXiv:2511.10653
First hybrid quantum-classical LLM for natural language generation. 10 qubits with 80 quantum gates replace ~10% of classical parameters in a 150M-parameter model with comparable convergence and generation quality.
2024/25 Theory
Barren Plateaus in Variational Quantum Computing (Review)
Larocca, Thanasilp, Wang, Cerezo et al. — arXiv:2405.00781
Comprehensive review unifying all four sources of barren plateaus: expressibility, global cost functions, noise, and entanglement. Identifies structure-preserving ansätze as the primary mitigation path.
2025 NLP/LLM Hybrid Q-C
Quantum-PEFT: Parameter-Efficient Fine-Tuning for QNNs
Various — 2025
LoRA-style low-rank reparameterisation applied to variational quantum circuits. Reduces trainable parameters while preserving expressibility and mitigating barren plateaus via constrained DLA dimension.
2025 Vision Hybrid Q-C
QMAE: Quantum Masked Autoencoders
Various — 2025
Self-supervised pretraining on quantum hardware via masked patch reconstruction. Quantum encoder learns compact latent representations; classical decoder reconstructs masked image patches.
2025 Hybrid Q-C Theory
FNQS: Foundation Networks for Quantum Systems
Various — 2025
Adapts GPT-style foundation model pretraining to quantum many-body systems. Uses classical shadows for efficient readout and QMAE-style SSL objectives on quantum hardware.
2025 Theory
Classical Shadows for Quantum Foundation Models
Various — 2025
Classical shadow tomography as an efficient readout protocol for large-scale quantum systems. Enables SSL training on quantum hardware with only $O(\log n)$ measurement overhead.
2025 Hardware Milestone
Quantinuum Helios: 56-Qubit Trapped-Ion Processor
Quantinuum — 2025
56 fully-connected qubits with >99.9% two-qubit gate fidelity, native mid-circuit measurement and reset, and all-to-all connectivity. Enables deep variational circuits with long coherence times ($T_2 \sim$ seconds).
2024
2024 Vision Hybrid Q-C
Quantum Vision Transformers (QViT)
Cherrat, Kerenidis, Mathur, Landman et al. — 2024
Replaces classical linear layers in ViT with orthogonal quantum layers constructed from Reconfigurable Beam Splitter (RBS) gates. Parameter count scales as $O(n)$ vs. $O(n^2)$ classical.
2024 Theory
Barren Plateaus from Dynamical Lie Algebras
Ragone & Larocca et al. — Nature Physics, 2024
Proves barren plateaus emerge from large DLA dimension. Circuits with exponentially large $|\mathfrak{g}|$ exhibit $\text{Var}[\partial_\mu E] \in O(1/2^n)$.
2024 NLP/LLM Hybrid Q-C
Quixer: A Quantum Transformer Model
Khatri, Matos, Coopmans et al. — Jun 2024
Full quantum self-attention via LCU and QSVT primitives. First quantum transformer applied to a practical language modelling task (Penn Treebank). Open-source implementation.
2024 NLP/LLM Hybrid Q-C
QTHA: Quantum Token-based Hybrid Attention
Various — 2024
Per-token quantum circuits compute attention weights. Quantum rotations parameterize the compatibility function; combines with classical feedforward layers.
2024 Generative Hybrid Q-C
Generative QML via Denoising Diffusion Probabilistic Models (QuDDPM)
Cacioppo, Bordoni et al. — Oct 2023
Replaces the classical score network with a variational quantum circuit. Decoherence channels provide a natural quantum noise schedule for the forward process.
2024 Generative Hybrid Q-C
Mixed-State Quantum DDPM (MSQuDDPM)
Various — Nov 2024
Mixed-state extension of QuDDPM; eliminates need for scrambling unitaries by adapting quantum noise channels directly to the model. Multi-resolution quantum circuit hierarchy.
Dec 2024 Hardware Milestone
Google Willow: Below-Threshold Quantum Error Correction
Google Quantum AI — December 2024
First experimental demonstration where increasing code distance decreases logical error rate (below-threshold QEC). 105 qubits; RCS task $10^{25}\times$ faster than classical supercomputers.
2023
2023 Algorithms Hybrid Q-C
Quantum-Enhanced Markov Chain Monte Carlo
Layden, Mazzola, Lam, Motta et al. — Nature 2023
Uses quantum coherence to propose non-local MCMC moves. Provably mixes faster than classical MCMC for certain target distributions. Demonstrated on 27-qubit IBM processors.
2023 Theory
Exponential Concentration in Quantum Kernel Methods
Thanasilp, Wang, Cerezo, Holmes — 2023
Shows kernel values concentrate exponentially in the number of qubits for random circuits, undermining quantum advantage claims. Identifies conditions for avoiding concentration.
2022
2022 Algorithms
TETRIS-ADAPT-VQE
Anastasiou, Sharma, Mayhall et al. — 2022
Problem-tailored ADAPT-VQE variant that simultaneously adds multiple operators forming a "tetromino" pattern in circuit space. Reduces circuit depth vs. vanilla ADAPT.
2022 Vision Theory
Quantum Convolutional Neural Networks
Cong, Choi, Lukin — Nature Physics 2019/2022
QCNNs mimic classical CNNs using alternating quantum convolution (local entangling) and pooling (partial measurement + feed-forward) layers. Efficient classically simulable special case.
2021
2021 NLP/LLM
lambeq: High-Level Python Library for Quantum NLP
Kartsaklis, Fan, Yeung, Pearson et al. — 2021
Implements DisCoCat framework: parses sentences to string diagrams, applies rewrite rules, translates to quantum circuits via functorial semantics. PyTorch & Qiskit backends.
2021 Algorithms
ADAPT-VQE: Adaptive Derivative-Assembled VQE
Grimsley, Economou, Barnes, Mayhall — 2021
Iteratively grows ansatz by selecting operators with largest gradient magnitude. Avoids barren plateaus via greedy circuit construction; achieves chemical accuracy with shallower circuits.
2009–20
2009 Algorithms
HHL: Quantum Algorithm for Linear Systems
Harrow, Hassidim, Lloyd — PRL 2009
Solves $A|x\rangle=|b\rangle$ in $O(\log N \cdot \kappa^2/\epsilon)$ for sparse, well-conditioned $A$. Exponential speedup over classical; caveats on state preparation and readout.
2019 Theory
Dequantization: Classical Algorithms for QML Tasks
Ewin Tang — 2019
Shows sampling-based classical algorithms achieve similar complexities to HHL for many ML tasks when given similar data access (quantum-inspired). Resets claims of quantum supremacy for ML.
2010–20 NLP/LLM
DisCoCat: Compositional Distributional Quantum NLP
Coecke, Sadrzadeh, Clark — 2010; Meichanetzidis et al. — 2020
Categorical framework: grammar → string diagram → quantum circuit. Noun meanings = quantum states; verbs = quantum channels. Meaning composition = circuit composition.
2019 Algorithms
QSVT: Quantum Singular Value Transformation
Gilyén, Su, Low, Wiebe — STOC 2019
Unifies quantum algorithms via block-encoding + quantum signal processing. Any polynomial $p(A/\alpha)$ can be applied to a block-encoded matrix. Subsumes HHL, phase estimation, amplitude amplification.
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Hardware Milestones

Key processors powering quantum ML research in the pre-fault-tolerant era.

Google Quantum AI
Willow
December 2024
  • 105 physical qubits (superconducting)
  • Below-threshold QEC — first ever demonstration
  • Error ∝ $e^{-d/d_0}$ with code distance $d$
  • RCS: $10^{25}\times$ classical supercomputer
  • Surface code distance 3, 5, 7 experiments
105 qubits Superconducting Below-threshold QEC
Quantinuum
Helios
2025
  • 56 fully-connected qubits (trapped ion)
  • $>99.9\%$ two-qubit gate fidelity
  • Native mid-circuit measurement & reset
  • All-to-all connectivity (no SWAP overhead)
  • Long coherence times: $T_2 \sim$ seconds
56 qubits Trapped Ion >99.9% fidelity
IBM Quantum
Heron r2
2024–2025
  • 156 qubits (fixed-frequency, tunable coupler)
  • Reduced crosstalk vs. Eagle/Falcon
  • Quantum volume 128+ per chip cluster
  • Backbone of IBM Quantum Network
  • Enables 1000+ qubit via modular linking
156 qubits Superconducting Tunable coupler
D-Wave
Advantage2 (Prototype)
2023–2024
  • ~7,000 qubits on Zephyr topology
  • 20 connections/qubit — densest D-Wave graph
  • Lower noise vs. Pegasus (Advantage1)
  • Optimised for combinatorial optimisation via QA
  • Hybrid solvers bridge classical + quantum workloads
~7000 qubits Quantum Annealing Zephyr
IonQ
Forte Enterprise
2024–2025
  • 35 algorithmic qubits (#AQ35)
  • Barium ion platform — dual-species (Ba⁺ + Yb⁺)
  • Native two-qubit gate: MS (Mølmer-Sørensen)
  • All-to-all connectivity — no SWAP overhead
  • Cloud-accessible via AWS Braket & Azure Quantum
35 #AQ Trapped Ion (Ba) Cloud
PsiQuantum
Photonic QC (Roadmap)
2026+ target
  • Silicon photonics — room-temperature operation
  • Fusion-based quantum computation (FBQC)
  • Targets millions of physical photonic qubits
  • Fault-tolerant architecture from the ground up
  • Manufactured on standard CMOS foundry processes
Photonic FBQC CMOS fab
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Key Conferences & Venues

Conferences publishing quantum ML, quantum computing, and hybrid AI research.

Conference Full Name Focus Typical Dates Submission
QIP Quantum Information Processing Core quantum computing, algorithms, QML theory Jan–Feb annually Sep–Oct prior year
NeurIPS Neural Information Processing Systems ML/DL including QML workshop tracks December annually May–Jun
ICML Int'l Conference on Machine Learning ML theory; QML workshop (QuantumML@ICML) July annually Jan–Feb
ICLR Int'l Conference on Learning Representations Deep learning; quantum-enhanced models April–May annually Sep–Oct prior year
APS March APS March Meeting Quantum hardware, condensed matter, QML March annually Nov prior year
IEEE QCE IEEE Int'l Conference on Quantum Computing & Engineering Engineering aspects of quantum computing September annually April
Nature Physics Nature Physics (journal) Flagship for experimental QML/hardware results Ongoing Continuous
PRX Quantum Physical Review X Quantum High-impact quantum computing & QML papers Ongoing Continuous
Quantum Quantum (Verein Quantenjournal) Open-access quantum information & algorithms Ongoing Continuous
AAAI QAI AAAI Workshop on Quantum AI AI applications of quantum computing February (with AAAI) Oct–Nov prior year

Key arXiv Categories to Follow

quant-ph
Quantum Physics
Algorithms, QML theory, hardware & error correction
cs.LG
Machine Learning
Hybrid QML, VQCs, quantum kernel methods
cs.CL
Computation & Language
Quantum NLP, DisCoCat, language transformers
cs.CV
Computer Vision
Quantum vision models, QViT, QCNN, QMAE