8,437 research outputs found
Resonant Quantum Search with Monitor Qubits
We present an algorithm for the generalized search problem (searching
marked items among items) based on a continuous Hamiltonian and exploiting
resonance. This resonant algorithm has the same time complexity
as the Grover algorithm. A natural extension of the algorithm, incorporating
auxiliary "monitor" qubits, can determine precisely, if it is unknown. The
time complexity of our counting algorithm is , similar to the best
quantum approximate counting algorithm, or better, given appropriate physical
resources.Comment: 12 pages, 1 figur
Nationality Classification Using Name Embeddings
Nationality identification unlocks important demographic information, with
many applications in biomedical and sociological research. Existing name-based
nationality classifiers use name substrings as features and are trained on
small, unrepresentative sets of labeled names, typically extracted from
Wikipedia. As a result, these methods achieve limited performance and cannot
support fine-grained classification.
We exploit the phenomena of homophily in communication patterns to learn name
embeddings, a new representation that encodes gender, ethnicity, and
nationality which is readily applicable to building classifiers and other
systems. Through our analysis of 57M contact lists from a major Internet
company, we are able to design a fine-grained nationality classifier covering
39 groups representing over 90% of the world population. In an evaluation
against other published systems over 13 common classes, our F1 score (0.795) is
substantial better than our closest competitor Ethnea (0.580). To the best of
our knowledge, this is the most accurate, fine-grained nationality classifier
available.
As a social media application, we apply our classifiers to the followers of
major Twitter celebrities over six different domains. We demonstrate stark
differences in the ethnicities of the followers of Trump and Obama, and in the
sports and entertainments favored by different groups. Finally, we identify an
anomalous political figure whose presumably inflated following appears largely
incapable of reading the language he posts in.Comment: 10 pages, 9 figures, 4 table, accepted by CIKM 2017, Demo and free
API: www.name-prism.co
Scalable and Flexible Classical Shadow Tomography with Tensor Networks
Classical shadow tomography is a powerful randomized measurement protocol for
predicting many properties of a quantum state with few measurements. Two
classical shadow protocols have been extensively studied in the literature: the
single-qubit (local) Pauli measurement, which is well suited for predicting
local operators but inefficient for large operators; and the global Clifford
measurement, which is efficient for low-rank operators but infeasible on
near-term quantum devices due to the extensive gate overhead. In this work, we
demonstrate a scalable classical shadow tomography approach for generic
randomized measurements implemented with finite-depth local Clifford random
unitary circuits, which interpolates between the limits of Pauli and Clifford
measurements. The method combines the recently proposed locally-scrambled
classical shadow tomography framework with tensor network techniques to achieve
scalability for computing the classical shadow reconstruction map and
evaluating various physical properties. The method enables classical shadow
tomography to be performed on shallow quantum circuits with superior sample
efficiency and minimal gate overhead and is friendly to noisy
intermediate-scale quantum (NISQ) devices. We show that the shallow-circuit
measurement protocol provides immediate, exponential advantages over the Pauli
measurement protocol for predicting quasi-local operators. It also enables a
more efficient fidelity estimation compared to the Pauli measurement.Comment: 15 pages + 1 page appendix, 10 figure
Measurement-Induced Criticality is Tomographically Optimal
We develop a classical shadow tomography protocol utilizing the randomized
measurement scheme based on hybrid quantum circuits, which consist of layers of
two-qubit random unitary gates mixed with single-qubit random projective
measurements. Unlike conventional protocols that perform all measurements by
the end of unitary evolutions, our protocol allows measurements to occur at any
spacetime position throughout the quantum evolution. We provide a universal
classical post-processing strategy to approximately reconstruct the original
quantum state from intermittent measurement outcomes given the corresponding
random circuit realizations over repeated experiments. We investigated the
sample complexity for estimating different observables at different measurement
rates of the hybrid quantum circuits. Our result shows that the sample
complexity has an optimal scaling at the critical measurement rate when the
hybrid circuit undergoes the measurement-induced transition.Comment: 6 pages, 4 figures + 13 pages appendice
Phase-fluctuation Induced Time-Reversal Symmetry Breaking Normal State
Spontaneous time-reversal symmetry (TRS) breaking plays an important role in
studying strongly correlated unconventional superconductors. When the
superconducting gap functions with different pairing symmetries compete, an
Ising () type symmetry breaking occurs due to the locking of the relative
phase via a second order Josephson coupling. The phase
locking can take place even in the normal state in the phase fluctuation regime
before the onset of superconductivity. If ,
then TRS is broken, otherwise, if , or, , rotational
symmetry is broken leading to a nematic state. In both cases, the order
parameters possess a 4-fermion structure beyond the scope of mean-field theory.
We employ an effective two-component -model assisted by a renormalization
group analysis to address this problem. In addition, a quartetting, or,
charge-``4e", superconductivity can also occur above . Monte-Carlo
simulations are performed and the results are in a good agreement with the
renormalization group analysis. Our results provide useful guidance for
studying novel symmetry breakings in strongly correlated superconductors.Comment: 4+ pages, 3 figures. References are added. Supplementary Material is
updated. Comments are welcom
Solitary pulmonary mass in a patient with a history of lymphoma: a case report
INTRODUCTION: With the progress made in treatments, the survival rate for patients with malignant lymphoma in the last 30 years has significantly improved. However, the risk of experiencing a second primary malignancy or other disease has increased significantly. CASE PRESENTATION: A 44-year-old Mongolian man with a large mass in his right lower abdomen was admitted to our hospital 15 years previously. The mass was removed, and confirmed via pathological examination to be a malignant B-cell lymphoma in the appendix and distal small bowel. Post-operative chemotherapy with standard cyclophosphamide, hydroxydaunomycin, vincristine (Oncovin®) and prednisolone regimen was given for six cycles. No obvious recurrence was detected over the following 12 years. Subsequently, a mass in the right lung was found on a regular X-ray follow-up; our patient did not report chills, fever or cough. Chest computed tomography and positron emission tomography scans confirmed the mass. A primary lung carcinoma was considered to be the most likely diagnosis. However, after an exploratory thoracotomy and right upper lobectomy was performed a pathological examination of tissue samples demonstrated a lung cryptococcal granuloma, with positive staining for periodic acid Schiff and periodic acid-silver metheramine. CONCLUSIONS: Compared to the normal population, second primary malignancy (in particular leukaemia and lung cancer) in patients with malignant lymphoma during their long-term survival has been seen occasionally. However, other diagnoses should also be considered such as pulmonary cryptococcosis. Other than computed-tomography-guided needle biopsy, surgery for some patients is a much more appropriate choice, which could also help attain correct diagnosis and treatment
- …