Handbook for Efficiently Quantifying Robustness of Magic

The nonstabilizerness, or magic, is an essential quantum resource to perform universal quantum computation. Robustness of magic (RoM) in particular characterizes the degree of usefulness of a given quantum state for non-Clifford operation. While the mathematical formalism of RoM can be given in a concise manner, it is extremely challenging to determine the RoM in practice, since it involves superexponentially many pure stabilizer states. In this work, we present efficient novel algorithms to compute the RoM. The crucial technique is a subroutine that achieves the remarkable features in calculation of overlaps between pure stabilizer states: (i) the time complexity per each stabilizer is reduced exponentially, (ii) the space complexity is reduced superexponentially. Based on this subroutine, we present algorithms to compute the RoM for arbitrary states up to $n=7$ qubits on a laptop, while brute-force methods require a memory size of 86 TiB. As a byproduct, the proposed subroutine allows us to simulate the stabilizer fidelity up to $n=8$ qubits, for which naive methods require memory size of 86 PiB so that any state-of-the-art classical computer cannot execute the computation. We further propose novel algorithms that utilize the preknowledge on the structure of target quantum state such as the permutation symmetry of disentanglement, and numerically demonstrate our state-of-the-art results for copies of magic states and partially disentangled quantum states. The series of algorithms constitute a comprehensive ``handbook'' to scale up the computation of the RoM, and we envision that the proposed technique applies to the computation of other quantum resource measures as well.Comment: 16+12 pages, 8+1 figure

Establishment of a myotube contractile force evaluation system using silicone gel and discovery of a novel myokine that enhances myotube mass and contractile force

東京都立大学Tokyo Metropolitan University博士（健康科学）doctoral thesi

Independent Three Resonance Conditions for Unity Transmission in Asymmetrical Rectangular Quadruple-Barrier Structures

Resonant tunneling transmission characteristics have been theoretically studied for asymmetrical rectangular quadruple-barrier structures with four different barriers. An analytical expression for transmission coefficient and resonance conditions has been derived. lt is found that unity resonant tunneling can occur at independent three desired energy levels simultaneously. This feature cannot be realized in double-or triple-barrier structures. The result may be useful in designing resonant tunneling devices in which each resonance energy for three wells is utilized independently

Reliable long-term operation of superconducting bus lines for the LHD

The Large Helical Device (LHD) is an experimental device for helical type fusion plasma in National Institute for Fusion Science and plasma experiments over 150,000 shots have been successfully conducted during twenty long-term plasma experimental campaigns. The LHD has two kinds of superconducting magnets and nine flexible superconducting bus lines with an average length of 55 m, which are utilized as a part of the current feeder system between the coils and the power sources. The superconducting bus lines consist of a pair of aluminum stabilized NbTi/Cu compacted stranded cable insulated electrically and coaxial five corrugated stainless steel tubes with two layers of vacuum insulations. The nominal current is 32 kA and the withstand voltage is 5 kV in 77 K gas helium. From the first experimental campaign, the superconducting bus lines have been stably operated at steady state by using automatic control. It is also confirmed that the status of the superconducting bus lines are kept good thanks to appropriate maintenances. As the results, the reliable operation of the superconducting bus lines has been achieved during the plasma experimental campaigns without any serious failure and the total operational time of the steady state cooling is approximately 58,000 hours

Effects of Subcooling on Lengths of Propagating Normal Zones in the LHD Helical Coils

Propagation of a short normal zone was observed in a helical coil of the Large Helical Device, when the coil was cooled with subcooled helium, of which the inlet and outlet temperatures are 3.2 K and below 4.0 K, respectively. The normal zone was induced at the bottom position of the coil. It propagated to only the downstream side of the current with recovery from the opposite side, and stopped after passing the outer equator of the torus. The induced balance voltage is obviously lower and the propagating time is shorter than those of propagating normal zones observed in the helical coil cooled with saturated helium at 4.4 K. According to the simulation of the propagation of a normal zone, it is considered that such a short normal zone at the current close to the minimum propagating current propagates without full transition to film boiling

Gait instability, ophthalmoplegia, and chorea with orofacial dyskinesia in a man with anti-Ri antibodies: a case report

A 79-year-old man was admitted for 2 weeks of dizziness, followed by diplopia, involuntary movement and progressive gait disturbances. Neurologic examination revealed horizontal and vertical gaze paresis, bilateral choreiform movement with orofacial dyskinesia, and limb/truncal ataxia. MRI revealed fluid-attenuated inversion recovery image-hyperintense signal abnormalities in the dorsal midbrain, pontine and medulla. Within another few days, the patient developed type II acute respiratory failure requiring artificial invasive ventilation. Because autoimmune encephalitis was suspected, he received intravenous immunoglobulin therapy followed by intravenous methylprednisolone, but only his ophthalmoplegia improved minimally. Serological tests were positive for anti-Ri onconeural antibodies. CT-guided mediastinal lymph node biopsy was performed and revealed small cell lung carcinoma. We report the rare manifestation of anti-Ri antibody-associated paraneoplastic neurological syndrome (PNS), and this case can alert us to the importance of respiratory management in this diverse neurologic disease. Furthermore, PNSs positive for anti-Ri antibodies should be added to the list of differential diagnoses of chorea with orofacial dyskinesia

Loxoprofen Sodium, a Non-Selective NSAID, Reduces Atherosclerosis in Mice by Reducing Inflammation

Recently, it is suggested that the use of nonsteroidal anti-inflammatory drugs (NSAID) may contribute to the occurrence of cardiovascular events, while the formation of atherosclerotic lesions is related to inflammation. Loxoprofen sodium, a non-selective NSAID, becomes active after metabolism in the body and inhibits the activation of cyclooxygenase. We fed apoE−/− mice a western diet from 8 to 16 weeks of age and administered loxoprofen sodium. We measured atherosclerotic lesions at the aortic root. We examined serum levels of cholesterol and triglycerides with HPLC, platelet aggregation, and urinary prostaglandin metabolites with enzyme immune assay. Atherosclerotic lesion formation was reduced to 63.5% and 41.5% as compared to the control in male and female apoE−/− mice treated with loxoprofen sodium respectively. Urinary metabolites of prostaglandin E2, F1α, and thromboxane B2, and platelet aggregation were decreased in mice treated with loxoprofen sodium. Serum levels of cholesterol and triglycerides were not changed. We conclude that loxoprofen sodium reduced the formation of early to intermediate atherosclerotic lesions at the proximal aorta in mice mediated by an anti-inflammatory effect

Reexamination of Refrigeration Power of the LHD Cryogenic System After Fire and Restart of Operation

The Large Helical Device (LHD), built in the 1990s, is a heliotron-type fusion plasma experimental device with the world\u27s first fully superconducting magnetic confinement system. The LHD cryogenic system operated stably for 18 years from 1998 to 2015 with high availability exceeding 99%. Unfortunately, in August 2015, a fire occurred in the cold box of the He refrigerator during maintenance, and nonmetallic components such as multilayer insulation films, temperature sensors, and measuring instruments were burnt down. Repair work started in November 2015 and completed at the end of July 2016. In August 2016, a test operation of the He refrigerator was conducted, and the refrigeration power was compared with that measured in the initial performance test conducted in 1995. The measured equivalent refrigeration power at 4.4 K was 9.19 kW, representing a decrease ~2% from the value of 9.38 kW measured in 1995. We attributed this slight decrease in refrigeration power to performance deterioration owing to aging over 18 years and not to the fire. The LHD restarted operation in January 2017, and its 19th operational cycle for a deuterium plasma experiment was conducted successfully up to August 2017. This paper reports the operational history and restart of the LHD superconducting magnet and cryogenic system

Conductor and joint test results of JT-60SA CS and EF coils using the NIFS test facility

In 2007, JAEA and NIFS launched the test project to evaluate the performance of cable-in-conduit (CIC) conductors and conductor joints for the JT-60SA CS and EF coils. In this project, conductor tests for four types of coil conductor and joint tests for seven types of conductor joint have been conducted for the past eight years using the NIFS test facility. As a result, the test project indicated that the CIC conductors and conductor joints fulfill the design requirement for the CS and EF coils. In addition, the NIFS test facility is expected to be utilized as the test facility for the development of a conductor and conductor joint for the purpose of the DEMO nuclear fusion power plant, provided that the required magnetic field strength is within 9 T