Nonlinear feedforward enabling quantum computation.

Measurement-based quantum computation with optical time-domain multiplexing is a promising method to realize a quantum computer from the viewpoint of scalability. Fault tolerance and universality are also realizable by preparing appropriate resource quantum states and electro-optical feedforward that is altered based on measurement results. While linear feedforward has been realized and become a common experimental technique, nonlinear feedforward was unrealized until now. In this paper, we demonstrate that a fast and flexible nonlinear feedforward realizes the essential measurement required for fault-tolerant and universal quantum computation. Using non-Gaussian ancillary states, we observed 10% reduction of the measurement excess noise relative to classical vacuum ancilla.

Low-loss polarization control in fiber systems for quantum computation.

Optical quantum information processing requires low loss interference of quantum light. Also, when the interferometer is composed of optical fibers, degradation of interference visibility due to the finite polarization extinction ratio becomes a problem. Here we propose a low loss method to optimize interference visibility by controlling the polarizations to a crosspoint of two circular trajectories on the Poincaré sphere. Our method maximizes visibility with low optical loss by using fiber stretchers as polarization controllers on both paths of the interferometer. We also experimentally demonstrate our method, where the visibility was maintained basically above 99.9% for three hours using fiber stretchers with an optical loss of 0.02 dB (0.5%). Our method makes fiber systems promising for practical fault-tolerant optical quantum computers.

Generation of highly pure single-photon state at telecommunication wavelength.

Telecommunication wavelength with well-developed optical communication technologies and low losses in the waveguide are advantageous for quantum applications. However, an experimental generation of non-classical states called non-Gaussian states at the telecommunication wavelength is still underdeveloped. Here, we generate highly-pure-single-photon states, one of the most primitive non-Gaussian states, by using a heralding scheme with an optical parametric oscillator and a superconducting nano-strip photon detector. The Wigner negativity, the indicator of non-classicality, of the generated single photon state is -0.228 ± 0.004, corresponded to 85.1 ± 0.7% of single photon and the best record of the minimum value at all wavelengths. The quantum-optics-technology we establish can be easily applied to the generation of various types of quantum states, opening up the possibility of continuous-variable-quantum-information processing at the telecommunication wavelength.

Quantum arbitrary waveform generator.

Controlling the temporal waveform of light is the key to a versatile light source in classical and quantum electronics. Although pulse shaping of classical light is mature and has been used in various fields, more advanced applications would be realized by a light source that generates arbitrary quantum light with arbitrary temporal waveforms. We call such a device a quantum arbitrary waveform generator (Q-AWG). The Q-AWG must be able to handle various quantum states of light, which are fragile. Thus, the Q-AWG requires a radically different methodology from classical pulse shaping. Here, we invent an architecture of Q-AWGs that can operate semi-deterministically at a repetition rate over gigahertz in principle. We demonstrate its core technology via generating highly nonclassical states with temporal waveforms that have never been realized before. This result would lead to powerful quantum technologies based on Q-AWGs such as practical optical quantum computing.

Laparoscopic isolated liver segmentectomy 8 for malignant tumors: techniques and comparison of surgical results with the open approach using a propensity score-matched study.

PURPOSE: Anatomic isolated liver segmentectomy 8 (ILSeg8) for malignancies remains technically challenging. The feasibility, safety, and oncologic validity of laparoscopic ILSeg8 are undefined, and thus were evaluated in comparison with the open approach. METHODS: This study enrolled 35 open and 29 laparoscopic ILSeg8 cases of hepatocellular carcinoma (n = 47), metastatic liver tumors (n = 16), and intrahepatic cholangiocarcinoma (n = 1) at our institution. The surgical techniques were based on the pre-hepatectomy extrahepatic Glissonian pedicle control, followed by cranial-to-caudal parenchymal dissection from the hepatic vein root side. The short- and long-term outcomes after ILSeg8 were retrospectively evaluated and compared between the open and laparoscopic approaches using 1:1 propensity score matching (PSM). RESULTS: Both before and after PSM, the laparoscopic ILSeg8 group had significantly less blood loss, lower postoperative serum bilirubin level, and a shorter postoperative hospital stay than the open group. The overall survival rates were comparable between the laparoscopic and open groups before (P = 0.017) and after (P = 0.043) PSM, with the similar recurrence-free survival rates between the groups. In a multivariable analysis of the cohort before PSM (n = 64), the laparoscopic approach was identified to be an independent factor for favorable overall survival (hazard ratio = 0.20, P = 0.039). CONCLUSION: Laparoscopic ILSeg8 using the extrahepatic Glissonian approach and hepatic vein root at first parenchymal dissection was feasible, safe, and oncologically acceptable. In ILSeg8 for malignancy, the laparoscopic approach potentially confers short-term advantages over the open approach with comparable long-term outcomes in select patients.

Efficient Backcasting Search for Optical Quantum State Synthesis.

Non-Gaussian states are essential for many optical quantum technologies. The so-called optical quantum state synthesizer (OQSS), consisting of Gaussian input states, linear optics, and photon-number resolving detectors, is a promising method for non-Gaussian state preparation. However, an inevitable and crucial problem is the complexity of the numerical simulation of the state preparation on a classical computer. This problem makes it very challenging to generate important non-Gaussian states required for advanced quantum information processing. Thus, an efficient method to design OQSS circuits is highly desirable. To circumvent the problem, we offer a scheme employing a backcasting approach, where the circuit of OQSS is divided into some sublayers, and we simulate the OQSS backwards from final to first layers. Moreover, our results show that the detected photon number by each detector is at most 2, which can significantly reduce the requirements for the photon-number resolving detector. By virtue of the potential for the preparation of a wide variety of non-Gaussian states, the proposed OQSS can be a key ingredient in general optical quantum information processing.

Generation of Schrödinger cat states with Wigner negativity using a continuous-wave low-loss waveguide optical parametric amplifier.

Continuous-wave (CW) squeezed light is used in the generation of various optical quantum states, and thus is a fundamental resource of fault-tolerant universal quantum computation using optical continuous variables. To realize a practical quantum computer, a waveguide optical parametric amplifier (OPA) is an attractive CW squeezed light source in terms of its THz-order bandwidth and suitability for modularization. The usages of a waveguide OPA in quantum applications thus far, however, are limited due to the difficulty of the generation of the squeezed light with a high purity. In this paper, we report the first observation of Wigner negativity of the states generated by a heralding method using a waveguide OPA. We generate Schrödinger cat states at the wavelength of 1545 nm with Wigner negativity using a quasi-single-mode ZnO-doped periodically poled LiNbO3 waveguide module we developed. Wigner negativity is regarded as an important indicator of the usefulness of the quantum states as it is essential in the fault-tolerant universal quantum computation. Our result shows that our waveguide OPA can be used in wide range of quantum applications leading to a THz-clock optical quantum computer.

The impact of chronic Epstein-Barr virus infection on the liver graft of pediatric liver transplant recipients: A retrospective observational study.

BACKGROUND: Chronic high Epstein-Barr virus loads (CHEBV) are commonly observed in pediatric liver transplant patients. However, it is unclear how CHEBV impacts the liver graft. The aim of this study was to clarify the clinical and pathological impacts of CHEBV on the liver graft. METHODS: From 2012 to 2020, we retrospectively investigated 46 pediatric liver transplant patients (under 16 years) who survived ≥6 months. The patients were divided into two groups: CHEBV group (EBV DNA >10 000 IU/ml of whole blood for ≥6 months) and nonchronic high EBV (NCHEBV) group (patients who did not meet CHEBV criteria). Tacrolimus was reduced to <3.0 ng/ml in patients with EBV DNA >5000 IU/ml. Blood biochemistry data and pathological findings, obtained at the time of protocol and episodic biopsies, were compared between the two groups. RESULTS: Out of 46 patients, 28 CHEBV and 18 NCHEBV patients were enrolled. The blood biochemical examination did not show a significant difference between the two groups. In addition, no significant differences between the two groups were found in the pathological findings, including frequency of late acute rejection and the progression of fibrosis at the time of both protocol and episodic biopsies. Appropriate adjustment of immunosuppression for CHEBV management may have contributed to the prevention of the progression of fibrosis. CONCLUSION: CHEBV had little adverse effect on the liver graft. Graft fibrosis might have been avoided through optimal dose modification of tacrolimus. Further long-term monitoring is necessary because CHEBV may affect the pediatric liver graft in the long term.

Wrapping double-mattress anastomosis for pancreaticojejunostomy in minimally invasive pancreaticoduodenectomy can significantly reduce postoperative pancreatic fistula rate compared with conventional pancreaticojejunostomy in open surgery: An analysis of a propensity score-matched sample.

BACKGROUND: Minimally invasive pancreaticoduodenectomy (MIPD), including laparoscopic pancreaticoduodenectomy (LPD) and robotic pancreaticoduodenectomy (RPD), is technically demanding because of pancreaticojejunostomy (PJ). Postoperative pancreatic fistula (POPF) is the most serious complication of MIPD and open pancreaticoduodenectomy (OPD). Contrary to expectations, conventional PJ in MIPD did not improve POPF rate and length of hospital stay. High POPF rates are attributed to technical issues encountered during MIPD, which include motion restriction and insufficient water tightness. Therefore, we developed wrapping double-mattress anastomosis, the Kiguchi method, which is a novel PJ technique that can improve MIPD. Herein, we describe the Kiguchi method for PJ in MIPD and compare the outcomes between this technique and conventional PJ in OPD. METHODS: The current retrospective study included 83 patients in whom the complete obstruction of the main pancreatic duct by pancreatic tumors was absent on preoperative imaging. This research was performed from September 2016 to August 2020 at Fujita Health University Hospital. All patients were evaluated as having a soft pancreatic texture, which is the most important factor associated with POPF development. Briefly, 50 patients underwent OPD with conventional PJ (OPD group). Meanwhile, 33 patients, including 15 and 18 who had LPD and RPD, respectively, underwent MIPD using the Kiguchi method (MIPD group). After a 1:1 propensity score matching, 30 patients in the OPD group were matched to 30 patients in the MIPD group. RESULTS: The patients' preoperative data did not differ. The grade B/C POPF rate was significantly lower in the MIPD group than in the OPD group (6.7% vs 40.0%, p = 0.002). The MIPD group had a significantly shorter median length of hospital stay than the OPD group (24 vs 30 days, p = 0.004). CONCLUSION: The novel Kiguchi method in MIPD significantly reduced the POPF rate in patients without complete obstruction of the main pancreatic duct.

Urgent intraoperative endovascular stent placement to resolve acute hepatic or portal venous obstruction during liver surgery: a case series.

BACKGROUND: Acute obstruction of the hepatic vein (HV) or the portal vein (PV), particularly when it occurs during liver surgery, is potentially fatal unless repaired swiftly. As surgical interventions for this problem are technically demanding and potentially unsuccessful, other treatment options are needed. CASE PRESENTATION: We report two cases of acute, surgically uncorrectable HV or PV obstruction during liver resection or living donor liver transplantation (LDLT), which was successfully treated with urgent intraoperative placement of endovascular stents using interventional radiology (IVR). In Case 1, a patient with colonic liver metastases underwent a non-anatomic partial hepatectomy of the segments 4 and 8 with middle hepatic vein (MHV) resection. Additionally, the patient underwent an extended right posterior sectionectomy with right hepatic vein (RHV) resection for tumors involving RHV. Reconstruction of the MHV was needed to avoid HV congestion of the anterior section of the liver. The MHV was firstly reconstructed by an end-to-end anastomosis between the MHV and RHV resected stumps. However, the reconstruction failed to retain the HV outflow and the anterior section became congested. Serial trials of surgical revisions including re-anastomosis, vein graft interposition and vein graft patch-plasty on the anastomotic wall failed to recover the HV outflow. In Case 2, a pediatric patient with biliary atresia underwent an LDLT and developed an intractable PV obstruction during surgery. Re-anastomosis with vein graft interposition failed to restore the PV flow and elongated warm ischemic time became critical. In both cases, the misalignment in HV or PV reconstruction was likely to have caused flow obstruction, and various types of surgical interventions failed to recover the venous flow. In both cases, an urgent IVR-directed placement of self-expandable metallic stents (SEMS) restored the HV or PV perfusion quickly and effectively, and saved the patients from developing critical conditions. Furthermore, in Cases 1 and 2, the SEMS placed were patent for a sufficient period of time (32 and 44 months, respectively). CONCLUSIONS: The IVR-directed, urgent, intraoperative endovascular stenting is a safe and efficient treatment tool that serves to resolve the potentially fatal acute HV or PV obstruction that occurs in the middle of liver surgery.

Antecedent Bile duct Cutting in the Glissonean pedicle technique (ABC technique) for extremely advanced perihilar cholangiocarcinoma.

BACKGROUND: In an increasing number of patients undergoing radical surgery for perihilar cholangiocarcinoma [1-3], the intrahepatic bile duct is conventionally transected after the vessels to be preserved or reconstructed are confirmed [3,4]. In patients with extremely advanced perihilar cholangiocarcinoma having massive vascular involvement, it is sometimes difficult to confirm the vessels for reconstruction because of restricted working space and/or anatomical variants, even after liver parenchymal dissection [4]. When the vessels cannot be confirmed, the tumor is usually unresectable [4]. METHODS: We developed a novel technique named "Antecedent Bile duct Cutting in the Glissonean pedicle technique (ABC technique)", in which we directly cut the bile duct in the Glissonean sheath under 5x loupe until the vessels to be reconstructed are secured. RESULTS: This video demonstrates the case of a 62-year-old man post-gastrectomy with a 47 × 36-mm perihilar cholangiocarcinoma with massive vascular involvement. Trisectionectomy was neither indicated left nor right due to excessively small remnant liver volume estimated even with portal vein embolization; thus, extended left hemihepatectomy with caudate lobectomy was applied using the ABC technique. Using the ABC technique after liver parenchymal dissection enabled us to identify and secure RAHA, RPHA, and RPV in favorable positions, and V5, RPV, RAHA, and RPHA were reconstructed. Finally, hepaticojejunostomy was performed. The operative time and blood transfusion were 1170 min and 1240 ml, respectively. R0 resection was achieved and the postoperative course was uneventful. CONCLUSION: ABC technique was technically feasible and useful for extremely advanced perihilar cholangiocarcinoma with massive vascular involvement.

Predictors of endothelial function improvement in patients with mild hypertriglyceridemia without evidence of coronary artery disease treated with purified eicosapentaenoic acid.

BACKGROUND AND AIMS: Eicosapentaenoic acid (EPA) has been reported to reduce cardiovascular risk in patients with hypertriglyceridemia. Although several mechanisms underlying the effects of EPA have been demonstrated, those responsible for its beneficial role in patients with hypertriglyceridemia without evidence of coronary artery disease (CAD) have not been fully elucidated. We sought to clarify the main factors associated with EPA administration that led to improved endothelial function. METHODS: Forty-seven consecutive patients with mild hypertriglyceridemia (mean age, 59 ± 13 years) without evidence of CAD were prospectively enrolled and administered purified EPA (1800 mg/day). Forty-four patients who were not administered EPA were enrolled as age- and sex-matched controls. Clinical variables and flow-mediated dilation (FMD) were examined before and after 6 months of treatment. Univariate and multivariate regression analyses were performed between FMD changes and clinical variables. RESULTS: EPA treatment decreased triglyceride levels (from 224.6 ± 58.8 to 151.8 ± 54.5 mg/dl, p < 0.001) and increased FMD (from 4.21% ± 1.91% to 6.21% ± 2.30%, p < 0.001). Multivariate analysis showed that the change in FMD was associated with the baseline high-density lipoprotein cholesterol (HDL-C) level (ß = -0.331, p = 0.027) and the change in EPA/arachidonic acid (AA) ratio (ß = 0.301, p = 0.048). CONCLUSIONS: EPA treatment improved triglyceride levels and FMD in patients with mild hypertriglyceridemia and without evidence of CAD. The baseline HDL-C level and the change in EPA/AA ratio predicted FMD improvement. The beneficial effects of EPA on triglyceride-rich lipoproteins and vascular endothelium may help improve endothelial function.

The Impact of Biliary Reconstruction Methods on Small Partial Liver Grafts.

Graft recipient weight ratios are lower in adult-to-adult living-donor liver transplantation than in adult-to-adult deceased-donor liver transplantation. Rapid liver regeneration is essential for increased recipient survival rates in adult-to-adult living-donor liver transplantation. However, the influence of biliary reconstruction methods, including choledocho-choledochostomy and choledocho-jejunostomy, on small partial liver grafts remains unknown. Herein, we investigate the impact of these biliary reconstruction methods on small partial liver grafts. METHODS: Male Lewis rats underwent isogenic arterialized 30% partial liver transplantation with small partial grafts, either via choledocho-jejunostomy or choledocho-choledochostomy. RESULTS: The 7-day survival rates of the choledocho-choledochostomy and choledocho-jejunostomy groups were 100% and 50%, respectively (P = 0.011). Choledocho-jejunostomy provoked reflux cholangitis, as confirmed by neutrophil infiltration around the bile ducts; suppressed and delayed liver regeneration in grafts, as confirmed by significant increases in intrahepatic interleukin-1ß level, significant decreases in the graft weight increase ratios, hepatocyte proliferation, and intrahepatic mRNA expression of vascular endothelial growth factor; and induced graft dysfunction, as confirmed by the presence of massive ascites, significantly decreased bile production, and prolonged elevation of total bilirubin, aspartate aminotransferase, and alanine aminotransferase. CONCLUSIONS: Choledocho-jejunostomy predisposed grafts to cholangitis, impaired liver regeneration, and aggravated animal survival, suggesting that choledocho-choledochostomy may be preferable over choledocho-jejunostomy in adult-to-adult living-donor liver transplantation.

Phase Locking between Two All-Optical Quantum Memories.

Optical approaches to quantum computation require the creation of multimode photonic quantum states in a controlled fashion. Here we experimentally demonstrate phase locking of two all-optical quantum memories, based on a concatenated cavity system with phase reference beams, for the time-controlled release of two-mode entangled single-photon states. The release time for each mode can be independently determined. The generated states are characterized by two-mode optical homodyne tomography. Entanglement and nonclassicality are preserved for release-time differences up to 400 ns, confirmed by logarithmic negativities and Wigner-function negativities, respectively.

Generation of time-domain-multiplexed two-dimensional cluster state.

Entanglement is the key resource for measurement-based quantum computing. It is stored in quantum states known as cluster states, which are prepared offline and enable quantum computing by means of purely local measurements. Universal quantum computing requires cluster states that are both large and possess (at least) a two-dimensional topology. Continuous-variable cluster states-based on bosonic modes rather than qubits-have previously been generated on a scale exceeding one million modes, but only in one dimension. Here, we report generation of a large-scale two-dimensional continuous-variable cluster state. Its structure consists of a 5- by 1240-site square lattice that was tailored to our highly scalable time-multiplexed experimental platform. It is compatible with Bosonic error-correcting codes that, with higher squeezing, enable fault-tolerant quantum computation.

All-Optical Storage of Phase-Sensitive Quantum States of Light.

We experimentally demonstrate storage and on-demand release of phase-sensitive, photon-number superposition states of the form α|0⟩+ße^{iθ}|1⟩ for an optical quantized oscillator mode. For this purpose, we newly developed a phase-probing mechanism compatible with a storage system composed of two concatenated optical cavities, which was previously employed for storage of phase-insensitive single-photon states [Phys. Rev. X 3, 041028 (2013)PRXHAE2160-330810.1103/PhysRevX.3.041028]. This is the first demonstration of all-optically storing highly nonclassical and phase-sensitive quantum states of light. The strong nonclassicality of the states after storage becomes manifest as a negative region in the corresponding Wigner function shifted away from the origin in phase space. This negativity is otherwise, without the phase information of the memory system, unobtainable. While our scheme includes the possibility of optical storage, on-demand release and synchronization of arbitrary single-rail qubit states, it is not limited to such states. In fact, our technique is extendible to more general phase-sensitive states such as multiphoton superposition or entangled states, and thus it represents a significant step toward advanced optical quantum information processing, where highly nonclassical states are utilized as resources.

Human Atrial Natriuretic Peptide in Cold Storage of Donation After Circulatory Death Rat Livers: An Old but New Agent for Protecting Vascular Endothelia?

BACKGROUND: Current critical shortage of donor organs has increased the use of donation after circulatory death (DCD) livers for transplantation, despite higher risk for primary nonfunction or ischemic cholangiopathy. Human atrial natriuretic peptide (hANP) is a cardiovascular hormone that possesses protective action to vascular endothelia. We aimed to clarify the therapeutic potential of hANP in cold storage of DCD livers. METHODS: Male Wistar rats were exposed to 30-minute warm ischemia in situ. Livers were then retrieved and cold-preserved for 6 hours with or without hANP supplementation. Functional and morphological integrity of the livers was evaluated by oxygenated ex vivo reperfusion at 37°C. RESULTS: hANP supplementation resulted in significant reduction of portal venous pressure (12.2 ± 0.5 versus 22.5 ± 3.5 mm Hg, P < 0.001). As underlying mechanisms, hANP supplementation significantly increased tissue adenosine concentration (P = 0.008), resulting in significant upregulation of endothelial nitric oxide synthase and significant downregulation of endothelin-1 (P = 0.01 and P = 0.004 vs. the controls, respectively). Consequently, hANP significantly decreased transaminase release (P < 0.001) and increased bile production (96.2 ± 18.2 versus 36.2 ± 15.2 µL/g-liver/h, P < 0.001). Morphologically, hepatocytes and sinusoidal endothelia were both better maintained by hANP (P = 0.021). Electron microscopy also revealed that sinusoidal ultrastructures and microvilli formation in bile canaliculi were both better preserved by hANP supplementation. Silver staining also demonstrated that hANP significantly preserved reticulin fibers in Disse space (P = 0.017), representing significant protection of sinusoidal frameworks/architectures. CONCLUSIONS: Supplementation of hANP during cold storage significantly attenuated cold ischemia/warm reperfusion injury of DCD livers.

Generation of a Cat State in an Optical Sideband.

We propose a method to subtract a photon from a double sideband mode of continuous-wave light. The central idea is to use phase modulation as a frequency sideband beam splitter in the heralding photon subtraction scheme, where a small portion of the sideband mode is down-converted to 0 Hz to provide a trigger photon. An optical cat state is created by applying the proposed method to a squeezed state at 500 MHz sideband, which is generated by an optical parametric oscillator. The Wigner function of the cat state reconstructed from a direct homodyne measurement of the 500 MHz sideband modes shows the negativity of W(0,0)=-0.088±0.001 without any loss corrections.