High-fidelity initialization and control of electron and nuclear spins in a four-qubit register

Single electron spins bound to multi-phosphorus nuclear spin registers in silicon have demonstrated fast (0.8 ns) two-qubit [Formula: see text] gates and long spin relaxation times (~30 s). In these spin registers, when the donors are ionized, the nuclear spins remain weakly coupled to their environment, allowing exceptionally long coherence times. When the electron is present, the hyperfine interaction allows coupling of the spin and charge degrees of freedom for fast qubit operation and control. Here we demonstrate the use of the hyperfine interaction to enact electric dipole spin resonance to realize high-fidelity ([Formula: see text]%) initialization of all the nuclear spins within a four-qubit nuclear spin register. By controllably initializing the nuclear spins to [Formula: see text], we achieve single-electron qubit gate fidelities of F = 99.78 ± 0.07% (Clifford gate fidelities of 99.58 ± 0.14%), above the fault-tolerant threshold for the surface code with a coherence time of [Formula: see text].

Socio-demographic Profile of COVID-19 Patients and Difficulties Faced by Them while Testing RT-PCR: A Multi-center Cross-sectional Study

This study was aimed to find out the socio-demographic profiles as well as difficulties of Reverse transcription polymerase chain reaction (RT-PCR) testing faced by Coronavirus Disease 2019 (COVID-19) patients. This cross-sectional study was conducted from 10th August to 7th September 2020. Data were collected by telephone interview using a pre-designed questionnaire after taking verbal consent from the participants. Out of 281 COVID-19 patients, 279 were diagnosed by RT-PCR; 10.3% were asymptomatic. Off them 67.6%were males, 24% were hospital staffs. Majority (66.2%) were from the non-city corporation area. History of recent contact with known COVID-19 patients was present in 56.9% cases. Fever (78.3%) and cough (58%) were the most common symptoms. One third of the patients faced difficulty to test RT-PCR for COVID-19. Sixteen percent patients complained of difficulty of getting serial for testing, the maximum waiting time was one week before giving samples. Thirty patients (10.8%) had to wait longer than usual time after reaching the center before giving sample. Hospital staffs were unable to co-operate in 2.5% of the patients while difficulty of managing transport to the hospital for suspected COVID-19 patient was an issue in 2.2% of the patients. Though testing was more difficult in city corporation areas (p=0.028), delay of getting test result was less (p<0.001). Maximum delay of getting test result was 10 days. Finding out the difficulties of COVID-19 testing will help to point out the issues behind these and will help to take necessary steps to tackle this matter. Testing rate can be increased to contain this highly contagious virus in this densely populated country.

A Comparison of Methods to Analyze Aquatic Heterotrophic Flagellates of Different Taxonomic Groups

Heterotrophic flagellates contribute significantly to the matter flux in aquatic and terrestrial ecosystems. Still today their quantification and taxonomic classification bear several problems in field studies, though these methodological problems seem to be increasingly ignored in current ecological studies. Here we describe and test different methods, the live-counting technique, different fixation techniques, cultivation methods like the liquid aliquot method (LAM), and a molecular single cell survey called aliquot PCR (aPCR). All these methods have been tested either using aquatic field samples or cultures of freshwater and marine taxa. Each of the described methods has its advantages and disadvantages, which have to be considered in every single case. With the live-counting technique a detection of living cells up to morphospecies level is possible. Fixation of cells and staining methods are advantageous due to the possible long-term storage and observation of samples. Cultivation methods (LAM) offer the possibility of subsequent molecular analyses, and aPCR tools might complete the deficiency of LAM in terms of the missing detection of non-cultivable flagellates. In summary, we propose a combination of several investigation techniques reducing the gap between the different methodological problems.