11 research outputs found
Effect of the interval between estrus onset 4 and artificial insemination on sex ratio 5 and fertility in cattle: a field study
P. 1264-1270We have carried out a field trial in cattle to study the effect of the interval between the onset of estrus and AI on sex ratio and fertility. Data were obtained from 716 cows that had been inseminated at different times between 8 and 44 h from the visual detection of estrus. Before analyzing the data, it was grouped in three intervals considering the time between estrus onset and AI (8â18, 18â30, and â„30 h). Our results show that the percentage of calved females (73.05%) is significantly superior for early inseminations (8â18 h), and it decreases 1.85% per hour from the onset of estrus. Delayed AIs (â„30 h) produce a significant deviation of the sex ratio towards the males (72.06%); nevertheless, fertility (percentage of successful pregnancies) diminishes significantly, from 66.19% (8â18 h) to 45.35% (â„30 h). In conclusion, variations in the interval between the onset of estrus and AI modify sex ratio. However, we must consider its effect on fertility.S
Sperm concentration at freezing affects post-thaw quality and fertility of ram semen
P. 1111-1118We have investigated the effect of sperm concentration in the freezing doses 200, 400, 800, and 1600 Ă 106 mLâ1 on the post-thaw quality and fertility of ram semen. Semen was collected from seven adult Churra rams by artificial vagina during the breeding season. The semen was diluted in an extender (TES-Tris-fructose, 20% egg yolk, and 4% glycerol), to a final concentration of 200, 400, 800, or 1600 Ă 106 mLâ1 and frozen. Doses were analyzed post-thawing for motility (computer-assisted sperm analysis system [CASA]), viability, and acrosomal status (fluorescence probes propidium iodide [PI]/peanut agglutinin conjugated with fluorescein thiocyanate (PNA-FITC), SYBR-14/PI [Invitrogen; Barcelona, Spain] and YO-PRO-1/PI [Invitrogen; Barcelona, Spain]). Total motility and velocity were lower for 1600 Ă 106 mLâ1 doses, while progressive motility and viability were lower both for 800 and 1600 Ă 106 mLâ1. The proportion of viable spermatozoa showing increased membrane permeability (YO-PRO-1+) rose in 800 and 1200 Ă 106 mLâ1. Intrauterine inseminations were performed with the 200, 400, and 800 Ă 106 mLâ1 doses at a fixed sperm number (25 Ă 106 per uterine horn) in synchronized ewes. Fertility (lambing rate) was similar for semen frozen at 200 (57.5%) or 400 Ă 106 mLâ1 (54.4%), whereas it was significantly lower for 800 Ă 106 mLâ1 (45.5%). In conclusion, increasing sperm concentration in cryopreserved semen, at least at 800 Ă 106 mLâ1 and more, adversely affects the postthawing quality and fertility of ram semen.S
Aplicación de técnicas de reproducción asistida en ovejas de raza Assaf
P. 129-132Aplicación de técnicas de reproducción asistida en ovejas de raza AssafS
Measurement-induced entanglement and teleportation on a noisy quantum processor
Measurement has a special role in quantum theory: by collapsing the
wavefunction it can enable phenomena such as teleportation and thereby alter
the "arrow of time" that constrains unitary evolution. When integrated in
many-body dynamics, measurements can lead to emergent patterns of quantum
information in space-time that go beyond established paradigms for
characterizing phases, either in or out of equilibrium. On present-day NISQ
processors, the experimental realization of this physics is challenging due to
noise, hardware limitations, and the stochastic nature of quantum measurement.
Here we address each of these experimental challenges and investigate
measurement-induced quantum information phases on up to 70 superconducting
qubits. By leveraging the interchangeability of space and time, we use a
duality mapping, to avoid mid-circuit measurement and access different
manifestations of the underlying phases -- from entanglement scaling to
measurement-induced teleportation -- in a unified way. We obtain finite-size
signatures of a phase transition with a decoding protocol that correlates the
experimental measurement record with classical simulation data. The phases
display sharply different sensitivity to noise, which we exploit to turn an
inherent hardware limitation into a useful diagnostic. Our work demonstrates an
approach to realize measurement-induced physics at scales that are at the
limits of current NISQ processors
Suppressing quantum errors by scaling a surface code logical qubit
Practical quantum computing will require error rates that are well below what
is achievable with physical qubits. Quantum error correction offers a path to
algorithmically-relevant error rates by encoding logical qubits within many
physical qubits, where increasing the number of physical qubits enhances
protection against physical errors. However, introducing more qubits also
increases the number of error sources, so the density of errors must be
sufficiently low in order for logical performance to improve with increasing
code size. Here, we report the measurement of logical qubit performance scaling
across multiple code sizes, and demonstrate that our system of superconducting
qubits has sufficient performance to overcome the additional errors from
increasing qubit number. We find our distance-5 surface code logical qubit
modestly outperforms an ensemble of distance-3 logical qubits on average, both
in terms of logical error probability over 25 cycles and logical error per
cycle ( compared to ). To investigate
damaging, low-probability error sources, we run a distance-25 repetition code
and observe a logical error per round floor set by a single
high-energy event ( when excluding this event). We are able
to accurately model our experiment, and from this model we can extract error
budgets that highlight the biggest challenges for future systems. These results
mark the first experimental demonstration where quantum error correction begins
to improve performance with increasing qubit number, illuminating the path to
reaching the logical error rates required for computation.Comment: Main text: 6 pages, 4 figures. v2: Update author list, references,
Fig. S12, Table I
Non-Abelian braiding of graph vertices in a superconducting processor
Indistinguishability of particles is a fundamental principle of quantum
mechanics. For all elementary and quasiparticles observed to date - including
fermions, bosons, and Abelian anyons - this principle guarantees that the
braiding of identical particles leaves the system unchanged. However, in two
spatial dimensions, an intriguing possibility exists: braiding of non-Abelian
anyons causes rotations in a space of topologically degenerate wavefunctions.
Hence, it can change the observables of the system without violating the
principle of indistinguishability. Despite the well developed mathematical
description of non-Abelian anyons and numerous theoretical proposals, the
experimental observation of their exchange statistics has remained elusive for
decades. Controllable many-body quantum states generated on quantum processors
offer another path for exploring these fundamental phenomena. While efforts on
conventional solid-state platforms typically involve Hamiltonian dynamics of
quasi-particles, superconducting quantum processors allow for directly
manipulating the many-body wavefunction via unitary gates. Building on
predictions that stabilizer codes can host projective non-Abelian Ising anyons,
we implement a generalized stabilizer code and unitary protocol to create and
braid them. This allows us to experimentally verify the fusion rules of the
anyons and braid them to realize their statistics. We then study the prospect
of employing the anyons for quantum computation and utilize braiding to create
an entangled state of anyons encoding three logical qubits. Our work provides
new insights about non-Abelian braiding and - through the future inclusion of
error correction to achieve topological protection - could open a path toward
fault-tolerant quantum computing
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Exponential suppression of bit or phase errors with cyclic error correction
Realizing the potential of quantum computing requires sufficiently low logical error rates1. Many applications call for error rates as low as 10-15 (refs. 2-9), but state-of-the-art quantum platforms typically have physical error rates near 10-3 (refs. 10-14). Quantum error correction15-17 promises to bridge this divide by distributing quantum logical information across many physical qubits in such a way that errors can be detected and corrected. Errors on the encoded logical qubit state can be exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold and stable over the course of a computation. Here we implement one-dimensional repetition codes embedded in a two-dimensional grid of superconducting qubits that demonstrate exponential suppression of bit-flip or phase-flip errors, reducing logical error per round more than 100-fold when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analysing error correlations with high precision, allowing us to characterize error locality while performing quantum error correction. Finally, we perform error detection with a small logical qubit using the 2D surface code on the same device18,19 and show that the results from both one- and two-dimensional codes agree with numerical simulations that use a simple depolarizing error model. These experimental demonstrations provide a foundation for building a scalable fault-tolerant quantum computer with superconducting qubits
Exponential suppression of bit or phase flip errors with repetitive error correction
Realizing the potential of quantum computing will require achieving
sufficiently low logical error rates. Many applications call for error rates in
the regime, but state-of-the-art quantum platforms typically have
physical error rates near . Quantum error correction (QEC) promises to
bridge this divide by distributing quantum logical information across many
physical qubits so that errors can be detected and corrected. Logical errors
are then exponentially suppressed as the number of physical qubits grows,
provided that the physical error rates are below a certain threshold. QEC also
requires that the errors are local and that performance is maintained over many
rounds of error correction, two major outstanding experimental challenges.
Here, we implement 1D repetition codes embedded in a 2D grid of superconducting
qubits which demonstrate exponential suppression of bit or phase-flip errors,
reducing logical error per round by more than when increasing the
number of qubits from 5 to 21. Crucially, this error suppression is stable over
50 rounds of error correction. We also introduce a method for analyzing error
correlations with high precision, and characterize the locality of errors in a
device performing QEC for the first time. Finally, we perform error detection
using a small 2D surface code logical qubit on the same device, and show that
the results from both 1D and 2D codes agree with numerical simulations using a
simple depolarizing error model. These findings demonstrate that
superconducting qubits are on a viable path towards fault tolerant quantum
computing