Temperature-Dependent Spin-Lattice Relaxation of the Nitrogen-Vacancy Spin Triplet in Diamond.

Spin-lattice relaxation within the nitrogen-vacancy (NV) center's electronic ground-state spin triplet limits its coherence times, and thereby impacts its performance in quantum applications. We report measurements of the relaxation rates on the NV center's |m_{s}=0⟩↔|m_{s}=±1⟩ and |m_{s}=-1⟩↔|m_{s}=+1⟩ transitions as a function of temperature from 9 to 474 K in high-purity samples. We show that the temperature dependencies of the rates are reproduced by an ab initio theory of Raman scattering due to second-order spin-phonon interactions, and we discuss the applicability of the theory to other spin systems. Using a novel analytical model based on these results, we suggest that the high-temperature behavior of NV spin-lattice relaxation is dominated by interactions with two groups of quasilocalized phonons centered at 68.2(17) and 167(12) meV.

One- and Two-Dimensional Nuclear Magnetic Resonance Spectroscopy with a Diamond Quantum Sensor.

We report on Fourier spectroscopy experiments performed with near-surface nitrogen-vacancy centers in a diamond chip. By detecting the free precession of nuclear spins rather than applying a multipulse quantum sensing protocol, we are able to unambiguously identify the NMR species devoid of harmonics. We further show that, by engineering different Hamiltonians during free precession, the hyperfine coupling parameters as well as the nuclear Larmor frequency can be selectively measured with up to five digits of precision. The protocols can be combined to demonstrate two-dimensional Fourier spectroscopy. Presented techniques will be useful for mapping nuclear coordinates in molecules deposited on diamond sensor chips, en route to imaging their atomic structure.

Quantum entanglement between an optical photon and a solid-state spin qubit.

Quantum entanglement is among the most fascinating aspects of quantum theory. Entangled optical photons are now widely used for fundamental tests of quantum mechanics and applications such as quantum cryptography. Several recent experiments demonstrated entanglement of optical photons with trapped ions, atoms and atomic ensembles, which are then used to connect remote long-term memory nodes in distributed quantum networks. Here we realize quantum entanglement between the polarization of a single optical photon and a solid-state qubit associated with the single electronic spin of a nitrogen vacancy centre in diamond. Our experimental entanglement verification uses the quantum eraser technique, and demonstrates that a high degree of control over interactions between a solid-state qubit and the quantum light field can be achieved. The reported entanglement source can be used in studies of fundamental quantum phenomena and provides a key building block for the solid-state realization of quantum optical networks.

Probing the dynamics of a nuclear spin bath in diamond through time-resolved central spin magnetometry.

Using fast electron spin resonance spectroscopy of a single nitrogen-vacancy defect in diamond, we demonstrate real-time readout of the Overhauser field produced by its nuclear spin environment under ambient conditions. These measurements enable narrowing the Overhauser field distribution by postselection, corresponding to a conditional preparation of the nuclear spin bath. Correlations of the Overhauser field fluctuations are quantitatively inferred by analyzing the Allan deviation over consecutive measurements. This method allows us to extract the dynamics of weakly coupled nuclear spins of the reservoir.

Nanoscale magnetic sensing with an individual electronic spin in diamond.

Detection of weak magnetic fields with nanoscale spatial resolution is an outstanding problem in the biological and physical sciences. For example, at a distance of 10 nm, the spin of a single electron produces a magnetic field of about 1 muT, and the corresponding field from a single proton is a few nanoteslas. A sensor able to detect such magnetic fields with nanometre spatial resolution would enable powerful applications, ranging from the detection of magnetic resonance signals from individual electron or nuclear spins in complex biological molecules to readout of classical or quantum bits of information encoded in an electron or nuclear spin memory. Here we experimentally demonstrate an approach to such nanoscale magnetic sensing, using coherent manipulation of an individual electronic spin qubit associated with a nitrogen-vacancy impurity in diamond at room temperature. Using an ultra-pure diamond sample, we achieve detection of 3 nT magnetic fields at kilohertz frequencies after 100 s of averaging. In addition, we demonstrate a sensitivity of 0.5 muT Hz(-1/2) for a diamond nanocrystal with a diameter of 30 nm.

Single-shot readout of multiple nuclear spin qubits in diamond under ambient conditions.

We use the electronic spin of a single nitrogen-vacancy defect in diamond to observe the real-time evolution of neighboring single nuclear spins under ambient conditions. Using a diamond sample with a natural abundance of (13)C isotopes, we first demonstrate high fidelity initialization and single-shot readout of an individual (13)C nuclear spin. By including the intrinsic (14)N nuclear spin of the nitrogen-vacancy defect in the quantum register, we then report the simultaneous observation of quantum jumps linked to both nuclear spin species, providing an efficient initialization of the two qubits. These results open up new avenues for diamond-based quantum information processing including active feedback in quantum error correction protocols and tests of quantum correlations with solid-state single spins at room temperature.

Environment-assisted precision measurement.

We describe a method to enhance the sensitivity of precision measurements that takes advantage of the environment of a quantum sensor to amplify the response of the sensor to weak external perturbations. An individual qubit is used to sense the dynamics of surrounding ancillary qubits, which are in turn affected by the external field to be measured. The resulting sensitivity enhancement is determined by the number of ancillas that are coupled strongly to the sensor qubit; it does not depend on the exact values of the coupling strengths and is resilient to many forms of decoherence. The method achieves nearly Heisenberg-limited precision measurement, using a novel class of entangled states. We discuss specific applications to improve clock sensitivity using trapped ions and magnetic sensing based on electronic spins in diamond.

Structural characterization of the saxitoxin-targeting APTSTX1 aptamer using optical tweezers and molecular dynamics simulations.

Optical tweezers have enabled the exploration of picoNewton forces and dynamics in single-molecule systems such as DNA and molecular motors. In this work, we used optical tweezers to study the folding/unfolding dynamics of the APTSTX1-aptamer, a single-stranded DNA molecule with high affinity for saxitoxin (STX), a lethal neurotoxin. By measuring the transition force during (un)folding processes, we were able to characterize and distinguish the conformational changes of this aptamer in the presence of magnesium ions and toxin. This work was supported by molecular dynamics (MD) simulations to propose an unfolding mechanism of the aptamer-Mg+2 complex. Our results are a step towards the development of new aptamer-based STX sensors that are potentially cheaper and more sensitive than current alternatives.

Studies into abstract properties of individuals. IV. Emergence In different aged needle primordia of Douglas fir.

Young, middle aged and older Douglas fir needle primordia, as determined by distance from the apical meristem, were measured and analyzed to compare levels and patterns of emergence related to development time. Emergence was seen in the differently aged needle primordia, generally most noticeable in the oldest and the least apparent in the youngest. There was also a negative relationship between variation in size and degree of emergence, and a positive one with variation in organization. The increasing level of emergence that appears with age can be related to the continual expression of information and the concomitant increase in complexity that marks ontogeny and is the result of diverging developmental trajectories. The histogenetic events seen in ontogeny can be interpreted as 'clocks' generating local time through the interactions among cells and tissues that make up the needle primordia. Emergent properties are manifested through the local events that mark ontogeny, and also through the expression of phylogenetic information, or the local expression of global (historical) levels of organization.

Studies into abstract properties of individuals. VI. The degree of emergence in individuals, populations, species and a three species lineage.

Emergent properties derived from the integration among descriptive variables were explored in three related grass species, Achnatherum lemmonii, Achnatherum hendersonii and Achnatherum wallowaensis. Different levels of organization were compared: individuals, populations, species, species-pairs and all three species combined. Emergence was seen at all levels with populations having the lowest degree followed by individuals, species and combinations of species. Because there were no variables unique to any level analyzed, emergence is more than the appearance of new structures. As the degree of emergence increases there is also an increase in variation in integration, the result of new growth rates. Time may explain the different degrees of emergence at the different levels. The trend populations-species-combination of species is easily related to time; the first are younger than the last. An individual develops over a greater period of time than a population. The greater time of existence of a species may account for a greater degree of emergence than an individual. In an individual the local time expressed during ontogeny establishes boundary conditions for an individual. As that local time becomes incorporated into global, or phylogenetic, time, the boundary conditions for taxa and lineages is established.

The complementarity of object-relations and instinct theory.

Object-relations theory implicitly assumes primary drives to cope with the fact that some kinds of transaction with objects are not gratifying but are feared and avoided. Fairbairn's conception of motivation assumes that there is an independent primary drive which may be called 'need for love', independent of other gratifications. Such an instinctual-drive concept is defined solely by its direction towards a goal, and rests on an arbitrary intuition as to the 'real' goal of observed behaviour. As Freud pointed out, what is required for the objective identification of a drive is the discovery of its physiological source. Freud recognised that a drive can be gratified only by a 'specific action' performed upon a suitable object, and that object relations set up in very early life are especially long-lasting. The concept of fixation can bridge the gap between infantile instinctual reactions and adult object relations.

Problems in the concept of repression and proposals for their resolution.

The authors of this paper accept the reality of the phenomenon of repression and consider that it alone explains many kinds of psychopathology. Nevertheless, the assumption in Freud's sketch of the mechanism of repression that the ego continually guards against the repressed impulse becoming conscious creates a logical problem. That would require that the ego remain aware of the repressed. A mental act becomes conscious only by being made the object of a second mental act, not through possessing intrinsic consciousness. Some barrier must be set up to prevent this second mental act. Freud's concept of primal repression is compared with Kleinian concepts of splitting and projection, which seem to avoid some of his difficulties. It is proposed that as a result of initial outburst of anxiety, neurological blockages are set up between the neural registrations of certain images of instinctual gratification and those other neural organisations that could register the occurrence of those images. The latter thus remain unknown, though still affecting behaviour. Neurological findings suggest that some such mechanism is possible.

Suppression of spin-bath dynamics for improved coherence of multi-spin-qubit systems.

Multi-qubit systems are crucial for the advancement and application of quantum science. Such systems require maintaining long coherence times while increasing the number of qubits available for coherent manipulation. For solid-state spin systems, qubit coherence is closely related to fundamental questions of many-body spin dynamics. Here we apply a coherent spectroscopic technique to characterize the dynamics of the composite solid-state spin environment of nitrogen-vacancy colour centres in room temperature diamond. We identify a possible new mechanism in diamond for suppression of electronic spin-bath dynamics in the presence of a nuclear spin bath of sufficient concentration. This suppression enhances the efficacy of dynamical decoupling techniques, resulting in increased coherence times for multi-spin-qubit systems, thus paving the way for applications in quantum information, sensing and metrology.

Repetitive readout of a single electronic spin via quantum logic with nuclear spin ancillae.

Robust measurement of single quantum bits plays a key role in the realization of quantum computation and communication as well as in quantum metrology and sensing. We have implemented a method for the improved readout of single electronic spin qubits in solid-state systems. The method makes use of quantum logic operations on a system consisting of a single electronic spin and several proximal nuclear spin ancillae in order to repetitively readout the state of the electronic spin. Using coherent manipulation of a single nitrogen vacancy center in room-temperature diamond, full quantum control of an electronic-nuclear system consisting of up to three spins was achieved. We took advantage of a single nuclear-spin memory in order to obtain a 10-fold enhancement in the signal amplitude of the electronic spin readout. We also present a two-level, concatenated procedure to improve the readout by use of a pair of nuclear spin ancillae, an important step toward the realization of robust quantum information processors using electronic- and nuclear-spin qubits. Our technique can be used to improve the sensitivity and speed of spin-based nanoscale diamond magnetometers.

Quantum register based on individual electronic and nuclear spin qubits in diamond.

The key challenge in experimental quantum information science is to identify isolated quantum mechanical systems with long coherence times that can be manipulated and coupled together in a scalable fashion. We describe the coherent manipulation of an individual electron spin and nearby individual nuclear spins to create a controllable quantum register. Using optical and microwave radiation to control an electron spin associated with the nitrogen vacancy (NV) color center in diamond, we demonstrated robust initialization of electron and nuclear spin quantum bits (qubits) and transfer of arbitrary quantum states between them at room temperature. Moreover, nuclear spin qubits could be well isolated from the electron spin, even during optical polarization and measurement of the electronic state. Finally, coherent interactions between individual nuclear spin qubits were observed and their excellent coherence properties were demonstrated. These registers can be used as a basis for scalable, optically coupled quantum information systems.

Studies into Abstract Properties of Individuals. III. A Study of Factors Affecting Emergence.

Eighteen individuals of Pinus ponderosa Lawson were analyzed for emergence, a difference in organization between the lower and higher levels of a within-plant hierarchy. The variables used were six distance measurements taken from needle cross sections, and organization was evaluated using angles between eigenvectors and a vector of isometry. Sixteen of 18 individuals analyzed showed emergence. Variation was shown in the degree of emergence, the between-level difference in organization. Variation in organization was the factor most strongly related to the degree of emergence; it also showed the strongest relationship to degree of emergence in grasses previously studied. These results argue for a possible cause and effect relationship between variation in organization and ontogeny or phylogeny, i.e., time-related irreversible change. The results also argue for the control of irreversible change residing in systems as a whole rather than their parts and for the direction of change being determined by the historical boundaries of those systems. Emergence is also related to the complexity that increases with the concomitant flows of energy and information in plants.

Monoclonal antibody A2B5, which detects cell surface antigens, binds to ganglioside GT3 (II3 (NeuAc)3LacCer) and to its 9-O-acetylated derivative.

The monoclonal antibody A2B5 recognizes antigens at the surface of neuronal and glial cells but also at the surface of thymus epithelia and pancreatic islet cells. Although these antigens have been characterized as polysialogangliosides, A2B5 also reacts with other unidentified gangliosides. In order to characterize further the epitope of A2B5, two new ganglioside antigens isolated from chicken brain are identified in this study. One is the ganglioside NeuAc alpha 2-8NeuAc alpha 2-8NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1ceramide (GT3) and the other is a 9-O-acetylated derivative of GT3). This derivative was purified from 10-day embryonic chicken brain. Acetyl groups substituted on sialic acid were removed either by alkali treatment or by incubation with influenza virus C, which contains receptor-destroying enzyme (a neuraminidate 9-O-acetyl esterase). The product of alkali treatment or viral action was detected by the antibody 18B8 which is specific for GT3. The deacetylated product still reacts with A2B5. These data and the results of mild oxidation of the antigen with sodium periodate suggest that the epitope recognized by antibody A2B5 contains the trisialyl structure found in GT3 but does not include the polyalcohol chain of the terminal sialic acid which can be oxidized by periodate or acetylated without modifying the affinity for the antibody. The epitope recognized by A2B5 is different from the epitope recognized by the antibody 18B8 in that 18B8 requires the three sialic acids with an intact and unsubstituted polyalcohol chain. Antibody 18B8 does not bind to 9-O-acetylated GT3 or GT3 oxidized by sodium periodate.

Postpartum sterilization in cesarean section and non-cesarean section deliveries: United States, 1970-75.

National Hospital Discharge Survey data indicate that the overall postpartum sterilization rate per 100 deliveries increased by 75 per cent from 4.0 in 1970 to 7.0 in 1975; by type of delivery, rates rose from 18.0 per 100 cesarean section deliveries and 3.2 for all other deliveries in 1970 to 19.0 and 5.6 respectively in 1975. The South had the highest postpartum sterilization rates overall. Deliveries to older mothers and cesarean section deliveries in hospitals with less than 100 beds were more often characterized by higher sterilization rates.

Demographic trends in tubal sterilization: United States, 1970-1978.

In the period 1970-1977, an estimated 4,236,000 women 15-44 years of age had tubal sterilization operations in United States hospitals. Both the number and the rate of tubal sterilizations increased each year from 1970-1977, but in 1978 both declined. Tubal sterilization rates for Black women were higher than for White women. Black women also tended to be younger at the time of tubal sterilization. For the nation as a whole, the mean age at the time of tubal sterilization remained constant at about 30 with the youngest age group having the highest proportion of never-married women.

Ectopic pregnancy in the United States 1970 through 1978.

Trends of the incidence and mortality associated with ectopic pregnancy (EP) in the United States were examined for 1970 through 1978. The estimated number of EPs rose from 17,800 in 1970 to 42,400 in 1978, and the EP incidence rate rose from 4.5 per 1,000 reported pregnancies to 9.4 during the same time period. The risk of EP was higher for older women and nonwhite women. Over 2.5% of all reported pregnancies among nonwhite women aged 35 to 44 years were ectopic. The death-to-case rate for EP declined almost 75% during the study period but remained consistently higher for nonwhite women as compared with white women.

PIP: 2 data sets from the National Center for Health Statistics were examined to study national trends in the occurrence of ectopic pregnancy (EP). 2 estimates of EP occurrence were calculated from the National Hospital Discharge Survey: 1) the number of EPs per 10,000 women aged 15-44 and 2) the number of EPs per 1000 reported pregnancies, which include EPs, legal abortions, and live births. From 1970-78, approximately 262,000 women aged 15-44 were discharged from US hospitals with a diagnosis of EP. The estimated number of EPs increased steadily from 17,800 in 1970 to 42,400 in 1978, while the EP rate/1000 reported pregnancies increased from 4.5 to 9.4. The EP rate/1000 reported pregnancies increased steadily with age, from 4.5 for women 15-25, 9.7 for women 25-34, to 15.2 for women 35-44. From 1970-78, the overall EP rate was 1.6 times higher for nonwhite than for white women. The EP rate for white women rose from 4.0/1000 reported pregnancies in 1970 to 8.4 in 1978, while for nonwhite women it rose from 7.1 to 12.5. The EP rate increased with age for both races. More than 1% of reported pregnancies in nonwhite women were ectopic; for nonwhite women aged 35-44 the rate was 2.6%. According to national vital statistics on mortality by cause, 437 women aged 15-44 died from EP between 1970 and 1978. The death-to-case rate declined more than 70% from 35 deaths/1000 EPs in 1970 to .9 in 1978. The death-to-case rate declined for both white and nonwhite women but remained consistenly higher for nonwhites. Overall the death-to-case rate for nonwhite women was 3.4 times that for white women. A likely cause of the marked increase in EP incidence between 1970-78 is pelvic inflammatory disease. Clinicians should consider the possibility of EP especially when treating nonwhite women over 35 who complain of menstrual irregularity and abdominal pain.