115 research outputs found
2-D Compass Codes
The compass model on a square lattice provides a natural template for
building subsystem stabilizer codes. The surface code and the Bacon-Shor code
represent two extremes of possible codes depending on how many gauge qubits are
fixed. We explore threshold behavior in this broad class of local codes by
trading locality for asymmetry and gauge degrees of freedom for stabilizer
syndrome information. We analyze these codes with asymmetric and spatially
inhomogeneous Pauli noise in the code capacity and phenomenological models. In
these idealized settings, we observe considerably higher thresholds against
asymmetric noise. At the circuit level, these codes inherit the bare-ancilla
fault-tolerance of the Bacon-Shor code.Comment: 10 pages, 7 figures, added discussion on fault-toleranc
Quantum Computation in Large Ion Crystals
Ion trap is one of the most promising candidates for quantum computing. High-fidelity gates have been demonstrated in small ion crystals and schemes like ion shuttling have been proposed for larger systems. This thesis discusses the possibility of direct quantum computing on a large ion crystal in a Paul trap, without any shuttling of the ions. We first review a scheme to entangle two ions in a small ion crystal mediated by the collective phonon modes and analyze the gate errors. The generalization to larger systems is divided into three parts. (1) We present numerical methods to solve all the normal modes of the ion crystal, including the micromotion, up to arbitrary precision. The stability of the crystal under infinitesimal perturbation is ensured when all the normal modes have real frequencies. For finite disturbance, direct molecular dynamics simulation will be needed; after discussing some potential problems in the simulation, we give a rule of thumb for the ion crystal to be stable at a given temperature. (2) We show that when designing an entangling gate between two nearby ions, all the ions far away can be neglected, so that only a small number of normal modes are relevant. Similarly, distant entangling gates can be applied in parallel and the crosstalk is shown to decay cubically with the distance between these gates. (3) Then we present numerical methods to include the solved micromotion into the design of the entangling gates efficiently, again up to arbitrary precision. Thus we conclude that the design and the implementing of entangling gates are scalable in a large ion crystal. Finally we consider a near-term application to simulate an all-to-all coupled Ising model in a small to medium-sized ion crystal.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/149953/1/wyukai_1.pd
Dual-Perspective Semantic-Aware Representation Blending for Multi-Label Image Recognition with Partial Labels
Despite achieving impressive progress, current multi-label image recognition
(MLR) algorithms heavily depend on large-scale datasets with complete labels,
making collecting large-scale datasets extremely time-consuming and
labor-intensive. Training the multi-label image recognition models with partial
labels (MLR-PL) is an alternative way, in which merely some labels are known
while others are unknown for each image. However, current MLP-PL algorithms
rely on pre-trained image similarity models or iteratively updating the image
classification models to generate pseudo labels for the unknown labels. Thus,
they depend on a certain amount of annotations and inevitably suffer from
obvious performance drops, especially when the known label proportion is low.
To address this dilemma, we propose a dual-perspective semantic-aware
representation blending (DSRB) that blends multi-granularity category-specific
semantic representation across different images, from instance and prototype
perspective respectively, to transfer information of known labels to complement
unknown labels. Specifically, an instance-perspective representation blending
(IPRB) module is designed to blend the representations of the known labels in
an image with the representations of the corresponding unknown labels in
another image to complement these unknown labels. Meanwhile, a
prototype-perspective representation blending (PPRB) module is introduced to
learn more stable representation prototypes for each category and blends the
representation of unknown labels with the prototypes of corresponding labels,
in a location-sensitive manner, to complement these unknown labels. Extensive
experiments on the MS-COCO, Visual Genome, and Pascal VOC 2007 datasets show
that the proposed DSRB consistently outperforms current state-of-the-art
algorithms on all known label proportion settings.Comment: Technical Report. arXiv admin note: text overlap with
arXiv:2203.0217
MC-SpEx: Towards Effective Speaker Extraction with Multi-Scale Interfusion and Conditional Speaker Modulation
The previous SpEx+ has yielded outstanding performance in speaker extraction
and attracted much attention. However, it still encounters inadequate
utilization of multi-scale information and speaker embedding. To this end, this
paper proposes a new effective speaker extraction system with multi-scale
interfusion and conditional speaker modulation (ConSM), which is called
MC-SpEx. First of all, we design the weight-share multi-scale fusers
(ScaleFusers) for efficiently leveraging multi-scale information as well as
ensuring consistency of the model's feature space. Then, to consider different
scale information while generating masks, the multi-scale interactive mask
generator (ScaleInterMG) is presented. Moreover, we introduce ConSM module to
fully exploit speaker embedding in the speech extractor. Experimental results
on the Libri2Mix dataset demonstrate the effectiveness of our improvements and
the state-of-the-art performance of our proposed MC-SpEx.Comment: Accepted by InterSpeech 202
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