Geriatric assessment measures are predictive of outcomes in chronic lymphocytic leukemia.

INTRODUCTION: Chronic lymphocytic leukemia (CLL) commonly affects older adults. However, few studies have examined the relationship between baseline geriatric domains and clinical outcomes in this population. Here, we aim to evaluate the use of a comprehensive geriatric assessment in older (>65 years) untreated patients with CLL to predict outcomes. MATERIALS AND METHODS: We conducted a planned analysis of 369 patients with CLL age 65 or older treated in a phase 3 randomized trial of bendamustine plus rituximab versus ibrutinib plus rituximab versus ibrutinib alone (A041202). Patients underwent evaluations of geriatric domains including functional status, psychological status, social activity, cognition, social support, and nutritional status. We examined associations among baseline geriatric domains with grade 3+ adverse events using multivariable logistic regression and overall survival (OS) and progression-free survival (PFS) using multivariable Cox regression models. RESULTS: In this study, the median age was 71 years (range: 65-87). In the combined multivariable model, the following geriatric domains were significantly associated with PFS: Medical Outcomes Study (MOS) - social activities survey score (hazard ratio [HR] [95% confidence interval (CI)] 0.974(0.961, 0.988), p = 0.0002) and nutritional status (≥5% weight loss in the preceding six months: (HR [95% CI] 2.717[1.696, 4.354], p < 0.001). MOS - social activities score [HR (95% CI) 0.978(0.958, 0.999), p = 0.038] was associated with OS. No geriatric domains were significantly associated with toxicity. There were no statistically significant interactions between geriatric domains and treatment. DISCUSSION: Geriatric domains of social activity and nutritional status were associated with OS and/or PFS in older adults with CLL. These findings highlight the importance of assessing geriatric domains to identify high-risk patients with CLL who may benefit from additional support during treatment.

Challenges in the Use of Quantum Computing Hardware-Efficient Ansätze in Electronic Structure Theory.

Advances in quantum computation for electronic structure, and particularly heuristic quantum algorithms, create an ongoing need to characterize the performance and limitations of these methods. Here we discuss some potential pitfalls connected with the use of hardware-efficient Ansätze in variational quantum simulations of electronic structure. We illustrate that hardware-efficient Ansätze may break Hamiltonian symmetries and yield nondifferentiable potential energy curves, in addition to the well-known difficulty of optimizing variational parameters. We discuss the interplay between these limitations by carrying out a comparative analysis of hardware-efficient Ansätze versus unitary coupled cluster and full configuration interaction, and of second- and first-quantization strategies to encode Fermionic degrees of freedom to qubits. Our analysis should be useful in understanding potential limitations and in identifying possible areas of improvement in hardware-efficient Ansätze.

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 H3S+ 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 generalize a qubit reduction technique termed entanglement forging or EF [A. Eddins et al., Phys. Rev. X Quantum, 2022, 3, 010309], currently restricted to the evaluation of ground-state energies, to the treatment of molecular properties. While in a conventional quantum simulation a qubit represents a spin-orbital, within EF a qubit represents a spatial orbital, reducing the number of required qubits by half. We combine the generalized EF with quantum subspace expansion [W. Colless et al., Phys. Rev. X, 2018, 8, 011021], a technique used to project the time-independent Schrodinger equation for ground- and excited-states in a subspace. To enable experimental demonstration of this algorithmic workflow, we deploy 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. This study is an important step towards the computational description of photo-dissociation on near-term quantum devices, as it can be generalized to other photodissociation processes and naturally extended in different ways to achieve more realistic simulations.

N-Electron Valence Perturbation Theory with Reference Wave Functions from Quantum Computing: Application to the Relative Stability of Hydroxide Anion and Hydroxyl Radical.

Quantum simulations of the hydroxide anion and hydroxyl radical are reported, employing variational quantum algorithms for near-term quantum devices. The energy of each species is calculated along the dissociation curve, to obtain information about the stability of the molecular species being investigated. It is shown that simulations restricted to valence spaces incorrectly predict the hydroxyl radical to be more stable than the hydroxide anion. Inclusion of dynamical electron correlation from nonvalence orbitals is demonstrated, through the integration of the variational quantum eigensolver and quantum subspace expansion methods in the workflow of N-electron valence perturbation theory, and shown to correctly predict the hydroxide anion to be more stable than the hydroxyl radical, provided that basis sets with diffuse orbitals are also employed. Finally, we calculate the electron affinity of the hydroxyl radical using an aug-cc-pVQZ basis on IBM's quantum devices.

The Use of Natural Language Processing to Assess Social Support in Patients With Advanced Cancer.

BACKGROUND: Data examining associations among social support, survival, and healthcare utilization are lacking in patients with advanced cancer. METHODS: We conducted a cross-sectional secondary analysis using data from a prospective longitudinal cohort study of 966 hospitalized patients with advanced cancer at Massachusetts General Hospital from 2014 through 2017. We used NLP to identify extent of patients' social support (limited versus adequate as defined by NLP-aided review of the Electronic Health Record (EHR)). Two independent coders achieved a Kappa of 0.90 (95% CI: 0.84-1.00) using NLP. Using multivariable regression models, we examined associations of social support with: 1) OS; 2) death or readmission within 90 days of hospital discharge; 3) time to readmission within 90 days; and 4) hospital length of stay (LOS). RESULTS: Patients' median age was 65 (range: 21-92) years, and a plurality had gastrointestinal (GI) cancer (34.3%) followed by lung cancer (19.5%). 6.2% (60/966) of patients had limited social support. In multivariable analyses, limited social support was not significantly associated with OS (HR = 1.13, P = 0.390), death or readmission (OR = 1.18, P = 0.578), time to readmission (HR = 0.92, P = 0.698), or LOS (ß = -0.22, P = 0.726). We identified a potential interaction suggesting cancer type (GI cancer versus other) may be an effect modifier of the relationship between social support and OS (interaction term P = 0.053). In separate unadjusted analyses, limited social support was associated with lower OS (HR = 2.10, P = 0.008) in patients with GI cancer but not other cancer types (HR = 1.00, P = 0.991). CONCLUSION: We used NLP to assess the extent of social support in patients with advanced cancer. We did not identify significant associations of social support with OS or healthcare utilization but found cancer type may be an effect modifier of the relationship between social support and OS. These findings underscore the potential utility of NLP for evaluating social support in patients with advanced cancer.

End-of-Life Care for Older Adults with Aggressive Non-Hodgkin Lymphoma.

Background: Aggressive non-Hodgkin lymphoma (NHL) commonly affects older adults and is often treated with intensive therapies. Receipt of intensive therapies and absence of a clear transition between the curative and palliative phases of treatment yield prognostic uncertainty and risk for poor end-of-life (EOL) outcomes. However, data regarding the EOL outcomes of this population are lacking. Methods: We conducted a retrospective analysis of adults ≥65 years with aggressive NHL treated with systemic therapy at Massachusetts General Hospital from April 2000 to July 2020 who subsequently died. We abstracted patient and clinical characteristics and EOL outcomes from the medical record. Using multivariable logistic regression, we examined factors associated with hospitalization within 30 days of death and hospice utilization. Results: Among 91 patients (median age = 75 years; 37.4% female), 70.3% (64/91) were hospitalized, 34.1% (31/91) received systemic therapy, and 23.3% (21/90) had an intensive care unit admission within 30 days of death. The rates of palliative care consultation and hospice utilization were 47.7% (42/88) and 39.8% (35/88), respectively. More than half of patients (51.6%, 47/91) died in a hospital or health care facility. In multivariable analysis, elevated lactic acid dehydrogenase was associated with risk of hospitalization within 30 days of death (odds ratio [OR] 3.61, p = 0.014). Palliative care consultation (OR 4.45, p = 0.005) was associated with a greater likelihood of hospice utilization, whereas hypoalbuminemia (OR 0.29, p = 0.026) was associated with a lower likelihood of hospice utilization. Conclusions: Older adults with aggressive NHL often experience high health care utilization and infrequently utilize hospice care at the EOL. Our findings underscore the need for interventions to optimize the quality of EOL care for this population.

Association of Social Support With Overall Survival and Healthcare Utilization in Patients With Aggressive Hematologic Malignancies.

BACKGROUND: Social support plays a crucial role for patients with aggressive hematologic malignancies as they navigate their illness course. The aim of this study was to examine associations of social support with overall survival (OS) and healthcare utilization in this population. METHODS: A cross-sectional secondary analysis was conducted using data from a prospective longitudinal cohort study of 251 hospitalized patients with aggressive hematologic malignancies at Massachusetts General Hospital from 2014 through 2017. Natural Language Processing (NLP) was used to identify the extent of patients' social support (limited vs adequate as defined by NLP-aided chart review of the electronic health record). Multivariable regression models were used to examine associations of social support with (1) OS, (2) death or readmission within 90 days of discharge from index hospitalization, (3) time to readmission within 90 days, and (4) index hospitalization length of stay. RESULTS: Patients had a median age of 64 years (range, 19-93 years), and most were White (89.6%), male (68.9%), and married (65.3%). A plurality of patients had leukemia (42.2%) followed by lymphoma (37.9%) and myelodysplastic syndrome/myeloproliferative neoplasm (19.9%). Using NLP, we identified that 8.8% (n=22) of patients had limited social support. In multivariable analyses, limited social support was associated with worse OS (hazard ratio, 2.00; P=.042) and a higher likelihood of death or readmission within 90 days of discharge (odds ratio, 3.11; P=.043), but not with time to readmission within 90 days or with index hospitalization length of stay. CONCLUSIONS: In this cohort of hospitalized patients with aggressive hematologic malignancies, we found associations of limited social support with lower OS and a higher likelihood of death or readmission within 90 days of hospital discharge. These findings underscore the utility of NLP for evaluating the extent of social support and the need for larger studies evaluating social support in patients with aggressive hematologic malignancies.

Distress in a Pandemic: Association of the Coronavirus Disease-2019 Pandemic with Distress and Quality of Life in Hematopoietic Stem Cell Transplantation.

The global coronavirus disease 2019 (COVID-19) pandemic has drastically disrupted cancer care, potentially exacerbating patients' distress levels. Patients undergoing hematopoietic stem cell transplantation (HSCT) may be especially vulnerable to this pandemic stress. However, the associations of the COVID-19 pandemic with distress, fatigue, and quality of life (QoL) are not well understood in this population. In a cross-sectional analysis of data from 205 patients undergoing HSCT enrolled in a supportive care trial, we compared baseline pre-HSCT distress symptoms (depression, anxiety, and posttraumatic stress disorder [PTSD]), fatigue, and QoL between enrollees before (ie, March 2019-January 2020) and during (ie, March 2020-January 2021) the COVID-19 pandemic. We used linear regression models adjusting for sociodemographics and cancer diagnosis to examine the associations between enrollment period and patient-reported outcomes. We used semistructured qualitative interviews in 20 allogeneic HSCT recipients who were ≥3-months post-HSCT to understand the impact of the COVID-19 pandemic on their recovery post-HSCT. One hundred twenty-four participants enrolled before COVID-19, and 81 participants enrolled during the pandemic. The 2 cohorts had similar baseline demographics and disease risk factors. In multivariate regression models, enrollment during COVID-19 was not associated with pre-HSCT symptoms of depression, anxiety, PTSD, fatigue, or QoL impairment. COVID-19-era participants reported themes of negative (eg, increased isolation) and positive (eg, engagement with meaningful activities) implications of the pandemic on HSCT recovery. We found no differences in pre-HSCT distress, fatigue, or QoL in patients undergoing HSCT before or during the COVID-19 pandemic; however, patients in early recovery post-HSCT report both negative and positive implications of the COVID-19 pandemic in their lives.

Palliative care and coping in patients with acute myeloid leukemia: Mediation analysis of data from a randomized clinical trial.

BACKGROUND: It has been shown previously that integrated palliative care for patients with acute myeloid leukemia (AML) during intensive chemotherapy leads to improvements in quality of life (QOL) and mood. Coping has been shown to mediate palliative care interventions in advanced cancer; the mechanisms by which improvements occur among patients with AML remain unexplained. METHODS: The authors conducted a secondary analysis of data from a multisite randomized trial of integrated palliative and oncology care (IPC; n = 86) versus usual care (n = 74) for hospitalized patients with AML undergoing intensive chemotherapy. IPC patients met with palliative care at least twice weekly during their initial and subsequent hospitalizations. Patients completed the Functional Assessment of Cancer Therapy-Leukemia, the Hospital Anxiety and Depression Scale, and the Brief Coping Orientation to Problems Experienced Inventory to assess QOL, mood, and coping at the baseline and at weeks 2, 4, 12, and 24. Linear regression models were used to assess the effect of IPC on coping. Causal mediation regression models were used to examine whether changes in coping mediated intervention effects on patient-reported outcomes at week 2. RESULTS: One hundred sixty eligible patients (68.1%) were enrolled. Those randomized to IPC reported improvements in approach-oriented coping (P < .01) and reductions in avoidant coping (P < .05). These changes in coping mediated the intervention effects on QOL (95% CI, 2.14-13.63), depression (95% CI, -2.05 to -0.27), and anxiety symptoms (95% CI, -1.25 to -0.04). Changes in approach-oriented and avoidant coping accounted for 78% of the total palliative care intervention effect on QOL, for 66% of the effect on depression, and for 35% of the effect on anxiety symptoms. CONCLUSIONS: Palliative care integrated during intensive chemotherapy for patients with AML facilitates coping strategy use. Improvement in coping skills accounts for a substantial proportion of the effect from a palliative care intervention on patient-reported outcomes.

Clinical Outcomes, Treatment Toxicity, and Health Care Utilization in Older Adults with Aggressive Non-Hodgkin Lymphoma.

BACKGROUND: Although balancing treatment efficacy with risks of complications is critical for older adults with aggressive non-Hodgkin lymphoma (NHL), few studies have described these patients' clinical outcomes, rates of toxicities, and health care utilization. METHODS: We conducted a retrospective analysis of adults ≥65 years diagnosed with aggressive NHL and receiving systemic therapy at Massachusetts General Hospital from April 2000 to July 2020. We abstracted patient characteristics, clinical outcomes, treatment toxicity, unplanned hospitalizations, and intensive care unit (ICU) admissions within 6 months of treatment initiation from the medical record. Using multivariable logistic regression, we examined factors associated with rates of grade 3+ nonhematologic toxicity and unplanned hospitalization. RESULTS: Among 295 patients (median age, 73 years; 39.0% female), 5-year overall survival (OS) was 74.2%. Five-year OS by age group (65-69, 70-74, 75-79, and 80+ years) was 82.2%, 72.0%, 73.6%, and 66.4%, respectively. Overall, 42.4% experienced grade 3+ toxicity, with 8.1% experiencing grades 4-5. The rates of unplanned hospitalization and ICU admission were 41.0% and 6.1%, respectively. In multivariable analysis, hypoalbuminemia (odds ratio [OR], 4.29; p < .001) and high comorbidity score (OR, 4.22; p < .001) were associated with likelihood of grade 3+ toxicity. Hypoalbuminemia (OR, 2.83; p = .003), high comorbidity score (OR, 3.93; p = .001), and receipt of EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin; OR, 5.45; p = .012) were associated with likelihood of unplanned hospitalization. CONCLUSIONS: The majority of older adults receiving upfront therapy for aggressive NHL survive beyond 5 years, yet nearly half experience substantial treatment toxicities and unplanned hospitalizations. Our findings underscore the need for supportive care interventions to enhance the care experience of this population. IMPLICATIONS FOR PRACTICE: The results of this study highlight the potential benefits of intensive chemoimmunotherapy for the majority of older adults with aggressive non-Hodgkin lymphoma, even at advanced ages. Nearly half of older adults experienced substantial treatment toxicities and unplanned hospitalizations, emphasizing the unmet need for supportive care interventions in this population. The present study also identified hypoalbuminemia and patient comorbidity score as factors associated with grade 3+ nonhematologic toxicity and unplanned hospitalization. These findings may guide the development and implementation of targeted supportive care interventions in high-risk older adults with aggressive non-Hodgkin lymphoma.

Anxiety and Depression Symptoms in Caregivers Prior to Hematopoietic Stem Cell Transplantation (HCT).

Family and friends caring for hematopoietic stem cell transplantation (HCT) recipients experience substantial disruptions in daily life as they prepare for transplant. These disruptions may increase their psychological distress, yet little research has described the extent of this distress. The goals of the present study were to characterize rates of anxiety and depression symptoms immediately prior to HCT and their relationship with modifiable caregiving domains. We conducted a secondary analysis of cross-sectional data of caregivers of patients undergoing HCT. Caregivers completed self-report measures to assess 8 domains of caregiving (Caregiver Oncology Quality of Life Questionnaire) and anxiety and depression symptoms (Hospital Anxiety and Depression Scale [HADS]) prior to transplant. Scores ≥8 on the HADS anxiety and depression subscales signified clinically significant symptoms. We used multivariable regression models adjusting for age, sex, caregiver relationship, and HCT type to examine the associations between caregiving domains and anxiety and depression symptoms. We enrolled 193 caregivers (median age = 60 years, 70.0% female, 52.3% allogeneic transplant). A majority of participants were providing care for a spouse (79.8%), followed by a child (7.8%) or parent (5.2%). On average, caregivers reported more anxiety (mean = 7.04, SD = 3.94) than depression symptoms (mean = 4.18, SD = 3.49), with 46.6% and 16.1% endorsing clinically significant anxiety and depression symptoms, respectively. Caregiver anxiety was associated with worse physical well-being, less leisure time, and poorer coping (Ps < .05). Caregiver depression symptoms were associated with worse physical well-being and less leisure time (Ps < .05). Caregivers of HCT recipients experience substantial psychological distress, particularly anxiety, prior to transplant. This distress is linked to modifiable caregiving domains. Study findings identify possible targets for psychosocial interventions aimed at managing caregiver anxiety and depression symptoms as well as highlight the need for intervention early during the course of transplant.

Quantum computation of dominant products in lithium-sulfur batteries.

Quantum chemistry simulations of some industrially relevant molecules are reported, employing variational quantum algorithms for near-term quantum devices. The energies and dipole moments are calculated along the dissociation curves for lithium hydride (LiH), hydrogen sulfide, lithium hydrogen sulfide, and lithium sulfide. In all cases, we focus on the breaking of a single bond to obtain information about the stability of the molecular species being investigated. We calculate energies and a variety of electrostatic properties of these molecules using classical simulators of quantum devices, with up to 21 qubits for lithium sulfide. Moreover, we calculate the ground-state energy and dipole moment along the dissociation pathway of LiH using IBM quantum devices. This is the first example, to the best of our knowledge, of dipole moment calculations being performed on quantum hardware.

Association Between Baseline Patient-Reported Outcomes and Complications of Hematopoietic Stem Cell Transplantation.

Hematopoietic cell transplantation (HCT) is a potentially curative therapy for hematologic malignancies, but it often results in significant toxicities and impaired quality of life (QOL). Although the value of patient-reported outcomes (PROs) is increasingly recognized in HCT, data are limited regarding the relationship between PROs and HCT complications. We conducted a secondary data analysis of 250 patients who were hospitalized for autologous or allogeneic HCT at Massachusetts General Hospital from 2011 through 2016. We assessed QOL (Functional Assessment of Cancer Therapy-General), mood (Hospital Anxiety and Depression Scale), and fatigue (FACT-Fatigue) at baseline. We abstracted from the Electronic Health Record (1) hospitalization during the first 100 days after HCT, (2) days alive and out of the hospital in the first 100 days after HCT, and (3) cumulative incidence of acute graft-versus-host disease (GVHD) among allogeneic HCT recipients. We assessed the association of baseline PROs with HCT complications using multivariable models adjusting for patient and transplant characteristics. Overall, 44.4% (111/250) of patients underwent an autologous HCT, 25.2% (63/250) received a myeloablative allogeneic HCT, and 30.4% (76/250) underwent a reduced-intensity allogeneic HCT. In multivariable logistic regression, higher anxiety (odds ratio [OR] = 1.14, P = .004) was associated with higher likelihood of rehospitalization within 100 days after HCT. In multivariable Poisson regression, lower fatigue (ß = 0.003, P = .015) was associated with increased days alive and out of the hospital in the first 100 days post-HCT. In multivariable logistic regression, lower baseline QOL (OR = 0.97, P = .034), higher fatigue (OR = 0.95, P = .004), and higher depression (OR = 1.15, P = .020) were associated with increased likelihood of acute GVHD. Baseline PROs are associated with health care utilization after HCT and risk of acute GVHD in allogeneic HCT recipients. These findings underscore the potential utility of pretransplantation PROs as important prognostic factors for HCT.

Computational Investigations of the Lithium Superoxide Dimer Rearrangement on Noisy Quantum Devices.

Quantum chemistry studies of biradical systems are challenging due to the required multiconfigurational nature of the wavefunction. In this work, Variational Quantum Eigensolver (VQE) is used to compute the energy profile for the lithium superoxide dimer rearrangement, involving biradical species, on quantum simulators and devices. Considering that current quantum devices can only handle limited number of qubits, we present guidelines for selecting an appropriate active space to perform computations on chemical systems that require many qubits. We show that with VQE performed with a quantum simulator reproduces results obtained with full-configuration interaction (Full CI) for the chosen active space. However, results deviate from exact values by about 39 mHa for calculations on a quantum device. This deviation can be improved to about 4 mHa using the readout mitigation approach and can be further improved to 2 mHa, approaching chemical accuracy, using the state tomography technique to purify the calculated quantum state.

Sharing and caring: The impact of social support on quality of life and health outcomes in hematopoietic stem cell transplantation.

BACKGROUND: Social support is crucial for successful recovery after hematopoietic stem cell transplantation (HSCT) and has the potential to affect patient quality of life (QOL) and health outcomes. However, there are limited data on the relationship between a patient's perception of his or her social support and these outcomes. METHODS: The authors conducted a secondary analysis of 250 autologous and allogeneic HSCT recipients enrolled in 2 supportive care trials at Massachusetts General Hospital from April 2011 through February 2016. They assessed social support as a patient's perception of his or her social well-being via the social well-being subscale of the Functional Assessment of Cancer Therapy. The authors used multivariate regression analyses to examine the relationship between pretransplant social well-being and QOL (Functional Assessment of Cancer Therapy-Treatment Outcome Index), psychological distress (Hospital Anxiety and Depression Scale), posttraumatic stress disorder [PTSD] symptoms (PTSD Checklist), fatigue (Functional Assessment of Cancer Therapy-Fatigue), and health care utilization (hospitalizations and days alive and out of the hospital) 6 months after HSCT. RESULTS: Participants were on average 56.4 years old (SD, 13.3 years); 44% (n = 110) and 56% (n = 140) received autologous and allogeneic HSCT, respectively. Greater pre-HSCT social well-being was associated with higher QOL (B = 0.10; 95% CI, 0.06-0.13; P < .001), lower psychological distress (B = -0.21; 95% CI, -0.29 to -0.12; P < .001), and lower PTSD symptoms (B = -0.12; 95% CI, -0.19 to -0.06; P < .001). Pre-HSCT social well-being was not significantly associated with fatigue or health care utilization 6 months after HSCT. CONCLUSIONS: Patients with higher pre-HSCT perceptions of their social support reported better QOL and lower psychological distress 6 months after HSCT. These findings underscore the potential for social support as a modifiable target for future supportive care interventions to improve the QOL and care of HSCT recipients.

Quantum simulation of electronic structure with a transcorrelated Hamiltonian: improved accuracy with a smaller footprint on the quantum computer.

Quantum simulations of electronic structure with a transformed Hamiltonian that includes some electron correlation effects are demonstrated. The transcorrelated Hamiltonian used in this work is efficiently constructed classically, at polynomial cost, by an approximate similarity transformation with an explicitly correlated two-body unitary operator. This Hamiltonian is Hermitian, includes no more than two-particle interactions, and is free of electron-electron singularities. We investigate the effect of such a transformed Hamiltonian on the accuracy and computational cost of quantum simulations by focusing on a widely used solver for the Schrödinger equation, namely the variational quantum eigensolver method, based on the unitary coupled cluster with singles and doubles (q-UCCSD) Ansatz. Nevertheless, the formalism presented here translates straightforwardly to other quantum algorithms for chemistry. Our results demonstrate that a transcorrelated Hamiltonian, paired with extremely compact bases, produces explicitly correlated energies comparable to those from much larger bases. For the chemical species studied here, explicitly correlated energies based on an underlying 6-31G basis had cc-pVTZ quality. The use of the very compact transcorrelated Hamiltonian reduces the number of CNOT gates required to achieve cc-pVTZ quality by up to two orders of magnitude, and the number of qubits by a factor of three.

Reducing Qubit Requirements for Quantum Simulations Using Molecular Point Group Symmetries.

Simulating molecules is believed to be one of the early stage applications for quantum computers. Current state-of-the-art quantum computers are limited in size and coherence; therefore, optimizing resources to execute quantum algorithms is crucial. In this work, we develop the second quantization representation of spatial symmetries, which are then transformed to their qubit operator representation. These qubit operator representations are used to reduce the number of qubits required for simulating molecules. We present our results for various molecules and elucidate a formal connection of this work with a previous technique that analyzed generic Z2 Pauli symmetries.

Quantum orbital-optimized unitary coupled cluster methods in the strongly correlated regime: Can quantum algorithms outperform their classical equivalents?

The Coupled Cluster (CC) method is used to compute the electronic correlation energy in atoms and molecules and often leads to highly accurate results. However, due to its single-reference nature, standard CC in its projected form fails to describe quantum states characterized by strong electronic correlations and multi-reference projective methods become necessary. On the other hand, quantum algorithms for the solution of many-electron problems have also emerged recently. The quantum unitary variant of CC (UCC) with singles and doubles (q-UCCSD) is a popular wavefunction Ansatz for the variational quantum eigensolver algorithm. The variational nature of this approach can lead to significant advantages compared to its classical equivalent in the projected form, in particular, for the description of strong electronic correlation. However, due to the large number of gate operations required in q-UCCSD, approximations need to be introduced in order to make this approach implementable in a state-of-the-art quantum computer. In this work, we evaluate several variants of the standard q-UCCSD Ansatz in which only a subset of excitations is included. In particular, we investigate the singlet and pair q-UCCD approaches combined with orbital optimization. We show that these approaches can capture the dissociation/distortion profiles of challenging systems, such as H4, H2O, and N2 molecules, as well as the one-dimensional periodic Fermi-Hubbard chain. These results promote the future use of q-UCC methods for the solution of challenging electronic structure problems in quantum chemistry.

Influence of Solvent on the Drug-Loading Process of Amphiphilic Nanogel Star Polymers.

We present an all-atom molecular dynamics study of the effect of a range of organic solvents (dichloromethane, diethyl ether, toluene, methanol, dimethyl sulfoxide, and tetrahydrofuran) on the conformations of a nanogel star polymeric nanoparticle with solvophobic and solvophilic structural elements. These nanoparticles are of particular interest for drug delivery applications. As drug loading generally takes place in an organic solvent, this work serves to provide insight into the factors controlling the early steps of that process. Our work suggests that nanoparticle conformational structure is highly sensitive to the choice of solvent, providing avenues for further study as well as predictions for both computational and experimental explorations of the drug-loading process. Our findings suggest that when used in the drug-loading process, dichloromethane, tetrahydrofuran, and toluene allow for a more extensive and increased drug-loading into the interior of nanogel star polymers of the composition studied here. In contrast, methanol is more likely to support shallow or surface loading and, consequently, faster drug release rates. Finally, diethyl ether should not work in a formulation process since none of the regions of the nanogel star polymer appear to be sufficiently solvated by it.