Generalized Quantum Signal Processing

The majority of prominent quantum algorithms, such as Hamiltonian simulation, quantum search, and factoring, can be fundamentally reduced to the central task of implementing a matrix function of a Hamiltonian. Quantum signal processing (QSP) currently stand as the most efficient technique for implementing such functions of block-encoded matrices.

Bath-Engineering Magnetic Order in Quantum Spin Chains: An Analytic Mapping Approach

Spin chains offer a versatile platform for the study of quantum materials. They can capture a wide range of complex and exotic phenomena from magnetic effects to topological phases. These effects are observed in a variety of materials, including quantum magnets, spin liquids, and quantum wires. Beyond ideal models, in reality, environmental degrees of freedom such as lattice phonons or engineered cavity modes couple to the spin degrees of freedom.

Fully passive measurement-device-independent quantum key distribution

The laws of quantum mechanics ensure theoretically secure communication using quantum key distribution (QKD) between two parties. However, practically implementing QKD systems is still a challenge due to the lack of perfect equipment. Hence, physicists have been working on eliminating side channels arising from these imperfections.

Finite-momentum and field-induced pairings in orbital-singlet spin-triplet superconductors

Superconductivity is conventionally understood as the condensation of electron pairs near the Fermi energy with momentum 𝐤 and −𝐤, i.e., a zero center-of-mass momentum, referred to as uniform pairing. A term in the Hamiltonian that breaks the degeneracy of the paired electrons generally suppresses the pairing.

Bypassing thermalization timescales in temperature estimation using prethermal probes

The classical notion of thermometry is rooted in the zeroth law of thermodynamics whereby the temperature of a sample is inferred using a small ancillary system, a probe. This probe is brought into contact with the sample until thermal equilibrium is reached. Subsequently, the temperature of the sample is inferred by measuring a physically relevant observable of the probe. From this protocol, it follows that an ideal probe should offer temperature estimates that are both accurate and rapid.

High-Order Randomized Compiler for Hamiltonian Simulation

Our work introduces a method called qSWIFT, a high-order randomized algorithm for Hamiltonian simulation. This method is a significant improvement over existing methods, such as qDRIFT, as it requires far fewer computational steps (or gates) to achieve the same level of precision. The qSWIFT algorithm is designed in such a way that the number of gates required does not depend on the number of terms in the Hamiltonian, making it more efficient for complex systems.

Spin Rotations in a Bose-Einstein Condensate Driven by Counterflow and Spin-Independent Interactions

Spin dynamics in cold atomic gases exhibit rich phenomena due to the interplay of particle interactions, quantum coherence, and particle statistics. In a Bose-Einstein condensate (BEC) with only contact interactions, spin dynamics can be induced by the spin dependence of the interaction strengths between particles. If interspin and intraspin interaction strengths are the same, on the other hand, there is only one scattering length, a.

Delta-T Flicker Noise Demonstrated with Molecular Junctions

Electronic flicker noise is the most abundant noise in electronic conductors. Here, we identify an unknown type of electronic flicker noise that is found when a temperature difference is applied across a nanoscale conductor. While this noise can be a performance-limiting factor, on the positive side, it can detect temperature differences across a large variety of nanoscale conductors, down to atomic-scale junctions with no special setup requirements.

Quantum repeaters: from quantum networks to the quantum internet

A quantum internet is the holy grail of quantum information processing, enabling the deployment of a broad range of quantum technologies and protocols on a global scale. However, numerous challenges must be addressed before the quantum internet can become a reality.

Discovery of charge order in a cuprate Mott insulator

High-temperature superconductivity (HTS) and charge density waves (CDW) are two prominent types of quantum electronic order that occur in cuprates. Using x-ray spectroscopy, muon spin rotation and electrical transport measurements on a special family of lanthanide-based cuprates, the authors have discovered a continuous evolution of the CDW order from the superconducting regime to the Mott insulator limit, indicating both HTS and CDW to be emergent phenomena of strong-correlation physics.

A Hybrid Quantum-Classical Algorithm for Multichannel Quantum Scattering of Atoms and Molecules

This paper proposes a hybrid quantum-classical algorithm for solving the time-independent Schrödinger equation for atomic and molecular collisions. It discovers that calculating scattering cross sections and rates for complex molecular collisions on NISQ quantum processors is possible. Some potential applications of their research include: scalable digital quantum computation of gas-phase bimolecular collisions and reactions of relevance to astrochemistry and ultracold chemistry.

Fully Passive Quantum Key Distribution

The authors have proposed a Quantum Key Distribution (QKD) scheme without any modulators, which removes a major source of side channels on QKD sources. The proposal suggests a new type of passive linear optical QKD source. This breakthrough can help improve the security of practical QKD systems.

Measurement optimization techniques for excited electronic states in near-term quantum computing algorithms

The authors investigate how to improve the quantum measurement efficiency for
the variational quantum eigensolver (VQE). Since VQE is one of the most popular near-term quantum algorithms for solving the electronic structure problem. They achieve this goal by investigating various measurement techniques to two widely used excited state VQE algorithms: multistate contraction and quantum subspace expansion.

Encrypted machine learning of molecular quantum properties

This paper discusses implementing Encrypted Machine Learning models by using oblivious transfer enabling, and secure predictions of molecular quantum properties. These secure and computationally feasible models can better protect privacy in chemistry and medical sciences, such as protecting customers' medical data. Overall, the team discusses recent findings and limitations of these models.

Emergent s -Wave Interactions between Identical Fermions in Quasi-One-Dimensional Geometries

Fermions sharing orbital excitation in a Bell-singlet are found to scatter with even exchange symmetry. This new collisional mode is enabled by a non-equilibrium occupation of the excited transverse state, which was at first unintentional -- a fortuitous impurity -- and later controlled in our experimental protocol. This finding points to new combinations of dimensionality and scattering symmetry.

Effective-Hamiltonian Theory of Open Quantum Systems at Strong Coupling

The paper presents a new theoretical framework that allows an analytical treatment of quantum systems at strong coupling with their surroundings, bringing deep understanding of the impact of strong system-bath coupling effects on open quantum system phenomena. It describes the application of this general approach to central problems in quantum thermodynamics such as quantum thermalization, heat transport, quantum refrigeration, nanoscale thermoelectric power generators & dissipative spin chains.

Characterization of State-Preparation Uncertainty in Quantum Key Distribution

The authors investigate how to create a secure quantum key distribution (QKD) by performing a proof-of-principle demonstration of the experimental techniques for characterizing the source phase and intensity fluctuation in commercial QKD systems.

Unitary p-wave interactions between fermions in an optical lattice

Researchers study how isolated pairs of atoms interact with each other. Namely, they observed a theoretical limit of p-wave forces for the first time. This paper provides insight into quantum simulations.