Rapamycin Rescues the Poor Developmental Capacity of Aged Porcine Oocytes

Unfertilized oocytes age inevitably after ovulation, which limits their fertilizable life span and embryonic development. Rapamycin affects mammalian target of rapamycin (mTOR) expression and cytoskeleton reorganization during oocyte meiotic maturation. The goal of this study was to examine the effects of rapamycin treatment on aged porcine oocytes and their in vitro development. Rapamycin treatment of aged oocytes for 24 h (68 h in vitro maturation [IVM]; 44 h+10 μM rapamycin/24 h, 47.52±5.68) or control oocytes (44 h IVM; 42.14±4.40) significantly increased the development rate and total cell number compared with untreated aged oocytes (68 h IVM, 22.04±5.68) (p<0.05). Rapamycin treatment of aged IVM oocytes for 24 h also rescued aberrant spindle organization and chromosomal misalignment, blocked the decrease in the level of phosphorylated-p44/42 mitogen-activated protein kinase (MAPK), and increased the mRNA expression of cytoplasmic maturation factor genes (MOS, BMP15, GDF9, and CCNB1) compared with untreated, 24 h-aged IVM oocytes (p<0.05). Furthermore, rapamycin treatment of aged oocytes decreased reactive oxygen species (ROS) activity and DNA fragmentation (p<0.05), and downregulated the mRNA expression of mTOR compared with control or untreated aged oocytes. By contrast, rapamycin treatment of aged oocytes increased mitochondrial localization (p<0.05) and upregulated the mRNA expression of autophagy (BECN1, ATG7, MAP1LC3B, ATG12, GABARAP, and GABARAPL1), anti-apoptosis (BCL2L1 and BIRC5; p<0.05), and development (NANOG and SOX2; p<0.05) genes, but it did not affect the mRNA expression of pro-apoptosis genes (FAS and CASP3) compared with the control. This study demonstrates that rapamycin treatment can rescue the poor developmental capacity of aged porcine oocytes

Flux-Driven Josephson Parametric Amplifier Fabricated Using the Nb/AlOx/Nb Trilayer Process

In this paper, we report a flux-driven Josephson parametric amplifier (JPA) fabricated using the Nb/AlOx/Nb Josephson junction process. The JPA consists of a parallel-plate type coupling capacitor and quarter-wavelength resonator terminated with a DC-SQUID. We adopt a simple process using well-established Nb trilayer technology. The overall configuration time of the Nb-based JPA can be shortened by measuring resonant frequency and its bias dependence in liquid helium. Amplification of the pre-tested device was demonstrated, showing a gain of 20 dB in a -3 dB bandwidth of 17 MHz in a 10 mK dilution fridge

Development of superconducting nanowire single photon detector (SNSPD) for communication wavelength of 1550 nm

We report our progress in the development of superconducting nanowire single photon detectors (SNSPDs). Single photon detector is the key component in quantum communication and quantum optics. Among various single photon detectors, SNSPDs show superior performance in detection efficiency, timing jitter, dark count, and count rate. We fabricate our devices with ultrathin niobium nitride (NbN) or amorphous molybdenum silicide (??-MoxSi1-x) films. 100 nm wide nanowire meander patterns are made on top of a distributed Bragg reflector (DBR). The detector is fiber-coupled and is operated below 2.5 K down to 0.8 K in a closed-cycle GM refrigerator. We use self-alignment scheme for the fiber-coupling in order to avoid possible drift due to the thermal contraction at low temperature. We present our measurement result of detection efficiency, dark count rate and reset time. We then discuss our further direction to increase the detector performance

Implementation of all-microwave entanglement schemes in 3D transmon two qubit system

We implemented all-microwave two qubit entanglement scheme via Stark shift-induced controlled phase gate, as suggested by J. Chow et al., [1]. Our system consists of two superconducting transmon qubits, one of which is a tunable-frequency qubit and the other is a fixed-frequency qubit, embedded in a three dimensional copper cavity. As we align higher quantum states outside the computational states, i.e., \textbar 12\textgreater and \textbar 03\textgreater , we could achieve controlled phase gate by applying a microwave tone which induces the Stark shift. The gate time can be controlled depending on how close we align the levels. We will present our results on the estimation of the fidelity of generated Bell states with tomographic reconstruction of the two-qubit states as a function of the gate time. [1] J. Chow et al., New J. Phys. 15, 115012 (2013)

Implementation of gate set tomography on transmon qubit to characterize and optimize single qubit

Characterizing the fidelities of quantum gates and improving them are essential requirements to build a scalable quantum computation platform. Two typical methods for such purpose, i.e., randomized benchmarking and quantum process tomography, contain drawbacks that cannot be compensated without the aid of the other, which demands the development of a new stand-alone protocol. Gate set tomography (GST) is one of such protocols developed to obtain detailed information of qubit gates that are free from the state preparation and measurement (SPAM) errors. We have implemented GST on several packages of single transmon qubit embedded in a 3 dimensional cavity. As a result, GST analysis not only estimated the process matrices of target gates but also suggested the direction for further calibration to achieve more accurate gate operations

Study on the squeezed microwave photon prepared by a Josephson parametric amplifier

Squeezed state is essential for detecting a weak signal with a reduced noise level. It can be prepared by using Josephson parametric amplifier (JPA) operating in the degenerate mode. We measured the gain by modulating the phase of local oscillator in homodyne setup and observed the gain level below the vacuum level indicating the formation of the squeezed state. Finally we reconstructed the quadrature tomographic histogram of the resulting squeezed state with Wigner function

Demonstration of Two-Qubit Algorithms in Superconducting Qubit System

Quantum computing platforms are expected to outperform their classical counterparts in solving certain technical problems such as factorization and searching process. With remarkable progresses in the field, a lot of efforts and attentions are being made to experimentally demonstrate such supremacy of quantum computation. As a primitive attempt, we have implemented simple and well-known two-qubit algorithms in our superconducting qubit system. Our system consists of two transmon qubits, one of which is a frequency-tunable qubit, embedded in a single copper cavity forming a circuit QED system. The entangling gate that is essential for implementing quantum algorithms has been realized by utilizing MAP (microwaveactivated phase) gate. We evaluate the performance of two-qubit processor by estimating the fidelity of the entangling gate with two-qubit quantum process tomography (QPT). Then we demonstrate the implementation of two-qubit algorithms such as Deutsch-Josza algorithm and Grover search