Simulating Open Quantum System Dynamics on NISQ Computers with Generalized Quantum Master Equations

We present a quantum algorithm based on the Generalized Quantum Master Equation (GQME) approach to simulate open quantum system dynamics on noisy intermediate-scale quantum (NISQ) computers. This approach overcomes the limitations of the Lindblad equation, which assumes weak system-bath coupling and Markovity, by providing a rigorous derivation of the equations of motion for any subset of elements of the reduced density matrix. The memory kernel resulting from the effect of the remaining degrees of freedom is used as input to calculate the corresponding non-unitary propagator. We demonstrate how the Sz.-Nagy dilation theorem can be employed to transform the non-unitary propagator into a unitary one in a higher-dimensional Hilbert space, which can then be implemented on quantum circuits of NISQ computers. We validate our quantum algorithm as applied to the spin-boson benchmark model by analyzing the impact of the quantum circuit depth on the accuracy of the results when the subset is limited to the diagonal elements of the reduced density matrix. Our findings demonstrate that our approach yields reliable results on NISQ IBM computers.Comment: 47 pages, 10 figures, updated to the most current version of the manuscrip

Exile Vol. XXXVII No. 1

And It Was Sunday by Julie Gruen 1-6 Like a Lady by Grace Mulvihill 7 The Final You by Eric Franzon 8 Joseph\u27s Children by Seneca Murley 9 Ain\u27t the 1950s Anymore by Ellen Stader 10-12 Bonding Women by Shannon salser 13 Ice Man (for mami 1905-1975) by Anne Mulligan 14 The Car Salesman by Tom Ream 15 Cancelling the Bunny by Stewart Engesser 16-17 Richard Brautigan\u27s Body by Michael Payne 18-19 Dinner in Barcelona by Holly Kurtz 20 Untitled by Margaret Strachen 21 Candles by Eric Franzon 22 Summer Rules by Jim Cox 23-31 My Boat by Holly Kurtz 32 Untitled by Michael Payne 33 Half the Birds in the City by Tiffany Richardson 34-35 Down Queen Anne Hill by Julie Gruen 36-37 Your Music by Tim Emrick 38 Zephyrs by Steve Corinth 39-41 Mother by Anne Mulligan 42 As I Look to the Sky, Maize by Shannon Salser 43-45 Close Book before Striking by Sarah Verdon 46-47 Smoked by Tom Ream 48 Driving through Rain by Stewart Engesser 49-50 Contributors 51 Editorial decision is shared equally among the Editorial Board. -i 35th Yea

Simulating Electronically Nonadiabatic Dynamics via the Generalized Quantum Master Equation

One of the greatest challenges facing computational chemistry is the simulation of electronically nonadiabatic dynamics. While there are several reduced dynamics methods for doing so, they often rely on restrictive assumptions such as weak coupling between the electronic and nuclear degrees of freedom (DOF) or between electronic states. An alternative approach for simulating nonadiabatic dynamics is via mixed quantum-classical (MQC) and quasiclassical (QC) methods which can handle strong coupling but their reliability and computational feasibility decrease with increasing simulation time. In comparison, the generalized quantum master equation (GQME) requires no approximation in its derivation and scales favorably with increasing simulation time. In the first chapter of this dissertation, two previous approaches to the GQME will be examined and a modified approach to the GQME (M-GQME) will be introduced. The two previous approaches are reliant on splitting the Hamiltonian into system, bath, and system-bath coupling terms which is neither natural nor convenient for simulating nonadiabatic dynamics. In comparison, the M-GQME is optimized for simulating nonadiabatic dynamics. Within the M-GQME, new protocols will be introduced for calculating the memory kernel via different MQC and QC methods. Through the application of the M-GQME to a spin-boson model with the memory kernel obtained via the Ehrenfest method, it will be shown that the M-GQME is more stable and robust compared to the previous approaches and that limiting the use of Ehrenfest to calculating the memory kernel enhances its accuracy in comparison to using it to directly simulate the system's dynamics. In the second chapter, two mapping Hamiltonian (MH) approaches with a QC approximation will be outlined and utilized to calculate the memory kernel of the M-GQME. These QC/MH methods have several advantages over the Ehrenfest method, including describing both the electronic and nuclear degrees of freedom as classical-like quantities and the ability to have non-Hermitian initial electronic states. By combining the QC/MH methods with the M-GQME on the spin-boson model, it will be shown that the M-GQME with the QC/MH methods outperforms both the M-GQME with Ehrenfest and the direct application of the QC/MH methods. In the third chapter, forty-four different methods for obtaining the memory kernel of the GQME are systematically explained and explored, including the three approaches previously discussed. The ability to calculate the memory kernel of the GQME is relatively new and a thorough examination of the different ways of obtaining the memory kernel has not been done. Through the study of these many approaches on the spin-boson model, the impact of the different approaches will be described and the benefits of the M-GQME compared to other approaches further solidified. In the fourth and fifth chapters, the M-GQME will be applied to models of the Fenna-Matthews-Olson (FMO) complex, a photosynthetic system, and the 2,6,-bis(methylene) adamantyl (BMA) radical cation, which contains a conical intersection. These two systems represent areas of considerable interest, given the prevalence of photosynthesis and conical intersections in biologically- and technologically-relevant systems. As will be shown, the success of the M-GQME with FMO and preliminary failure with BMA illuminates future areas where the M-GQME is expected to succeed along with the limitations of its application.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/168061/1/emulvi_1.pd

Tensor-Train Thermo-Field Memory Kernels for Generalized Quantum Master Equations

The generalized quantum master equation (GQME) approach provides a rigorous framework for deriving the exact equation of motion for any subset of electronic reduced density matrix elements (e.g., the diagonal elements). In the context of electronic dynamics, the memory kernel and inhomogeneous term of the GQME introduce the implicit coupling to nuclear motion and dynamics of electronic density matrix elements that are projected out (e.g., the off-diagonal elements), allowing for efficient quantum dynamics simulations. Here, we focus on benchmark quantum simulations of electronic dynamics in a spin-boson model system described by various types of GQMEs. Exact memory kernels and inhomogeneous terms are obtained from short-time quantum-mechanically exact tensor-train thermo-field dynamics (TT-TFD) simulations and are compared with those obtained from an approximate linearized semiclassical method, allowing for assessment of the accuracy of these approximate memory kernels and inhomogeneous terms. Moreover, we have analyzed the computational cost of the full and reduced-dimensionality GQMEs. The scaling of the computational cost is dependent on several factors, sometimes with opposite scaling trends. The TT-TFD memory kernels can provide insights on the main sources of inaccuracies of GQME approaches when combined with approximate input methods and pave the road for the development of quantum circuits that implement GQMEs on digital quantum computers

Fluorescence and phosphorescence lifetime imaging reveals a significant cell nuclear viscosity and refractive index changes upon DNA damage

Abstract Cytoplasmic viscosity is a crucial parameter in determining rates of diffusion-limited reactions. Changes in viscosity are associated with several diseases, whilst nuclear viscosity determines gene integrity, regulation and expression. Yet how drugs including DNA-damaging agents affect viscosity is unknown. We demonstrate the use of a platinum complex, Pt[L]Cl, that localizes efficiently mostly in the nucleus as a probe for nuclear viscosity. The phosphorescence lifetime of Pt[L]Cl is sensitive to viscosity and provides an excellent tool to investigate the impact of DNA damage. We show using Fluorescence Lifetime Imaging (FLIM) that the lifetime of both green and red fluorescent proteins (FP) are also sensitive to changes in cellular viscosity and refractive index. However, Pt[L]Cl proved to be a more sensitive viscosity probe, by virtue of microsecond phosphorescence lifetime versus nanosecond fluorescence lifetime of FP, hence greater sensitivity to bimolecular reactions. DNA damage was inflicted by either a two-photon excitation, one-photon excitation microbeam and X-rays. DNA damage of live cells causes significant increase in the lifetime of either Pt[L]Cl (HeLa cells, 12.5–14.1 µs) or intracellularly expressed mCherry (HEK293 cells, 1.54–1.67 ns), but a decrease in fluorescence lifetime of GFP from 2.65 to 2.29 ns (in V15B cells). These values represent a viscosity change from 8.59 to 20.56 cP as well as significant changes in the refractive index (RI), according to independent calibration. Interestingly DNA damage localized to a submicron region following a laser microbeam induction showed a whole cell viscosity change, with those in the nucleus being greater than the cytoplasm. We also found evidence of a by-stander effect, whereby adjacent un-irradiated cells also showed nuclear viscosity change. Finally, an increase in viscosity following DNA damage was also observed in bacterial cells with an over-expressed mNeonGreen FP, evidenced by the change in its lifetime from 2.8 to 2.4 ns

The creation of federal services for crippled children, 1890-1941

This historical study examines the factors that led to the creation of a federal program of services for crippled children in the United States during the 1930s. Established as part of the Social Security Act (SSA) of 1935, the Crippled Children Services (CCS) program was one of the first medical programs for children supported by the federal government. As early as the 1890s, many state and local governments developed services for crippled children through private and public efforts, making the federal government a relative late comer to supporting the needs of children with significant physical handicaps due to disease, birth defects and accidents. The development of a national reform agenda based on state and local efforts for crippled children began during the Progressive Era and culminated during the New Deal Era with the passage of the SSA. Several factors influenced the creation of the federal CCS program including the role of reformers and professional groups, the role of state-level private charities and children's institutions, and the increasing authority of the federal government in social programs. Under the SSA, states and territories quickly developed state-level CCS programs during the late 1930s. The United States Children's Bureau (USCB) administered the program for the federal government and helped states to incorporate preventive services and interdisciplinary approaches to service provision into state-level CCS programs. Factors that influenced the implementation of these programs included the availability of matching state funds, the establishment of state programs for crippled children prior to the SSA, and the accessibility of qualified health care professionals and facilities. The United States entry into World War II in 1941 slowed the growth of state-level CCS programs until 1945, and serves as a natural end point to this study. (Published By University of Alabama Libraries