Phase diagram at finite temperature and quark density in the strong coupling limit of lattice QCD for color SU(3)

We study the phase diagram of quark matter at finite temperature (T) and finite chemical potential (mu) in the strong coupling limit of lattice QCD for color SU(3). We derive an analytical expression of the effective free energy as a function of T and mu, including baryon effects. The finite temperature effects are evaluated by integrating over the temporal link variable exactly in the Polyakov gauge with anti-periodic boundary condition for fermions. The obtained phase diagram shows the first order phase transition at low temperatures and the second order phase transition at high temperatures separated by the tri-critical point in the chiral limit. Baryon has effects to reduce the effective free energy and to extend the hadron phase to a larger mu direction at low temperatures.Comment: 18 pages, 10 figure

Analytical formulation of the second-order derivative of energy for orbital-optimized variational quantum eigensolver: application to polarizability

We develop a quantum-classical hybrid algorithm to calculate the analytical second-order derivative of the energy for the orbital-optimized variational quantum eigensolver (OO-VQE), which is a method to calculate eigenenergies of a given molecular Hamiltonian by utilizing near-term quantum computers and classical computers. We show that all quantities required in the algorithm to calculate the derivative can be evaluated on quantum computers as standard quantum expectation values without using any ancillary qubits. We validate our formula by numerical simulations of quantum circuits for computing the polarizability of the water molecule, which is the second-order derivative of the energy with respect to the electric field. Moreover, the polarizabilities and refractive indices of thiophene and furan molecules are calculated as a testbed for possible industrial applications. We finally analyze the error-scaling of the estimated polarizabilities obtained by the proposed analytical derivative versus the numerical one obtained by the finite difference. Numerical calculations suggest that our analytical derivative may require fewer measurements (runs) on quantum computers than the numerical derivative to achieve the same fixed accuracy.Comment: 34 + 4 page

ADAPT-QSCI: Adaptive Construction of Input State for Quantum-Selected Configuration Interaction

We present a quantum-classical hybrid algorithm for calculating the ground state and its energy of the quantum many-body Hamiltonian by proposing an adaptive construction of a quantum state for the quantum-selected configuration interaction (QSCI) method. QSCI allows us to select important electronic configurations in the system to perform CI calculation (subspace diagonalization of the Hamiltonian) by sampling measurement for a proper input quantum state on a quantum computer, but how we prepare a desirable input state has remained a challenge. We propose an adaptive construction of the input state for QSCI in which we run QSCI repeatedly to grow the input state iteratively. We numerically illustrate that our method, dubbed \textit{ADAPT-QSCI}, can yield accurate ground-state energies for small molecules, including a noisy situation for eight qubits where error rates of two-qubit gates and the measurement are both as large as 1\%. ADAPT-QSCI serves as a promising method to take advantage of current noisy quantum devices and pushes forward its application to quantum chemistry.Comment: 14 page

Variational Quantum Simulation for Periodic Materials

We present a quantum-classical hybrid algorithm that simulates electronic structures of periodic systems such as ground states and quasiparticle band structures. By extending the unitary coupled cluster (UCC) theory to describe crystals in arbitrary dimensions, we numerically demonstrate in hydrogen chain that the UCC ansatz implemented on a quantum circuit can be successfully optimized with a small deviation from the exact diagonalization over the entire range of the potential energy curves. Furthermore, with the aid of the quantum subspace expansion method, in which we truncate the Hilbert space within the linear response regime from the ground state, the quasiparticle band structure is computed as charged excited states. Our work establishes a powerful interface between the rapidly developing quantum technology and modern material science.Comment: 6 + 1 pages, 3 + 1 figure

Orbital optimized unitary coupled cluster theory for quantum computer

We propose an orbital optimized method for unitary coupled cluster theory (OO-UCC) within the variational quantum eigensolver (VQE) framework for quantum computers. OO-UCC variationally determines the coupled cluster amplitudes and also molecular orbital coefficients. Owing to its fully variational nature, first-order properties are readily available. This feature allows the optimization of molecular structures in VQE without solving any additional equations. Furthermore, the method requires smaller active space and shallower quantum circuit than UCC to achieve the same accuracy. We present numerical examples of OO-UCC using quantum simulators, which include the geometry optimization of the water and ammonia molecules using analytical first derivatives of the VQE

Phosphate and Klotho

Klotho is a putative aging suppressor gene encoding a single-pass transmembrane co-receptor that makes the fibroblast growth factor (FGF) receptor specific for FGF-23. In addition to multiple endocrine organs, Klotho is expressed in kidney distal convoluted tubules and parathyroid cells, mediating the role of FGF-23 in bone–kidney–parathyroid control of phosphate and calcium. Klotho–/– mice display premature aging and chronic kidney disease-associated mineral and bone disorder (CKD-MBD)-like phenotypes mediated by hyperphosphatemia and remediated by phosphate-lowering interventions (diets low in phosphate or vitamin D; knockouts of 1α-hydroxylase, vitamin D receptor, or NaPi cotransporter). CKD can be seen as a state of hyperphosphatemia-induced accelerated aging associated with Klotho deficiency. Humans with CKD experience decreased Klotho expression as early as stage 1 CKD; Klotho continues to decline as CKD progresses, causing FGF-23 resistance and provoking large FGF-23 and parathyroid hormone increases, and hypovitaminosis D. Secreted Klotho protein, formed by extracellular clipping, exerts FGF-23-independent phosphaturic and calcium-conserving effects through its paracrine action on the proximal and distal tubules, respectively. We contend that decreased Klotho expression is the earliest biomarker of CKD and the initiator of CKD-MBD pathophysiology. Maintaining normal phosphate levels with phosphate binders in patients with CKD with declining Klotho expression is expected to reduce mineral and vascular derangements

Transition from tunneling to direct contact in tungsten nanojunctions

We apply the mechanically controllable break junctions technique to investigate the transition from tunneling to direct contact in tungsten. This transition is quite different from that of other metals and is determined by the local electronic properties of the tungsten surface and the relief of the electrodes at the point of their closest proximity. The conductance traces show a rich variety of patterns from the avalanche-like jump to a mesoscopic contact to the completely smooth transition between direct contact and tunneling. Due to the occasional absence of an adhesive jump the conductance of the contact can be continuously monitored at ultra-small electrode separations. The conductance histograms of tungsten are either featureless or show two distinct peaks related to the sequential opening of spatially separated groups of conductance channels. The role of surface states of tungsten and their contribution to the junction conductance at sub-Angstrom electrode separations are discussed.Comment: 6 pages, 6 figure

Quantum chemistry simulation of ground- and excited-state properties of the sulfonium cation on a superconducting quantum processor

The computational description of correlated electronic structure, and particularly of excited states of many-electron systems, is an anticipated application for quantum devices. An important ramification is to determine the dominant molecular fragmentation pathways in photo-dissociation experiments of light-sensitive compounds, like sulfonium-based photo-acid generators used in photolithography. Here we simulate the static and dynamical electronic structure of the H$_3$S$^+$ molecule, taken as a minimal model of a triply-bonded sulfur cation, on a superconducting quantum processor of the IBM Falcon architecture. To this end, we combine a qubit reduction technique with variational and diagonalization quantum algorithms, and use a sequence of error-mitigation techniques. We compute dipole structure factors and partial atomic charges along ground- and excited-state potential energy curves, revealing the occurrence of homo- and heterolytic fragmentation. To the best of our knowledge, this is the first simulation of a photo-dissociation reaction on a superconducting quantum device, and an important step towards the computational description of photo-dissociation by quantum computing algorithms.Comment: 12 pages, 7 figure

Status and overview of development of the Silicon Pixel Detector for the PHENIX experiment at the BNL RHIC

We have developed a silicon pixel detector to enhance the physics capabilities of the PHENIX experiment. This detector, consisting of two layers of sensors, will be installed around the beam pipe at the collision point and covers a pseudo-rapidity of | \eta | < 1.2 and an azimuth angle of | \phi | ~ 2{\pi}. The detector uses 200 um thick silicon sensors and readout chips developed for the ALICE experiment. In order to meet the PHENIX DAQ readout requirements, it is necessary to read out 4 readout chips in parallel. The physics goals of PHENIX require that radiation thickness of the detector be minimized. To meet these criteria, the detector has been designed and developed. In this paper, we report the current status of the development, especially the development of the low-mass readout bus and the front-end readout electronics.Comment: 9 pages, 8 figures and 1 table in DOCX (Word 2007); PIXEL 2008 workshop proceedings, will be published in the Proceedings Section of JINST(Journal of Instrumentation

Evidence of a new state in 11^{11}Be observed in the 11^{11}Li β\beta-decay

Coincidences between charged particles emitted in the $\beta$-decay of $^{11}$Li were observed using highly segmented detectors. The breakup channels involving three particles were studied in full kinematics allowing for the reconstruction of the excitation energy of the $^{11}$Be states participating in the decay. In particular, the contribution of a previously unobserved state at 16.3 MeV in $^{11}$Be has been identified selecting the $\alpha$ + $^7$He$\to\alpha$ + $^6$He+n channel. The angular correlations between the $\alpha$ particle and the center of mass of the $^6$He+n system favors spin and parity assignment of 3/2$^-$ for this state as well as for the previously known state at 18 MeV.Comment: 13 pages, 6 figure