Quantum error correction is an indispensable ingredient for scalable quantum computing. In this Perspective we discuss a particular class of quantum codes called “quantum low-density parity-check ...(LDPC) codes.” The codes we discuss are alternatives to the surface code, which is currently the leading candidate to implement quantum fault tolerance. We introduce the zoo of quantum LDPC codes and discuss their potential for making quantum computers robust with regard to noise. In particular, we explain recent advances in the theory of quantum LDPC codes related to certain product constructions and discuss open problems in the field.
Defects in silicon carbide (SiC) have emerged as a favorable platform for optically active spin-based quantum technologies. Spin qubits exist in specific charge states of these defects, where the ...ability to control these states can provide enhanced spin-dependent readout and long-term charge stability. We investigate this charge state control for two major spin qubits in 4H-SiC, the divacancy and silicon vacancy, obtaining bidirectional optical charge conversion between the bright and dark states of these defects. We measure increased photoluminescence from divacancy ensembles by up to three orders of magnitude using near-ultraviolet excitation, depending on the substrate, and without degrading the electron spin coherence time. This charge conversion remains stable for hours at cryogenic temperatures, allowing spatial and persistent patterning of the charge state populations. We develop a comprehensive model of the defects and optical processes involved, offering a strong basis to improve material design and to develop quantum applications in SiC.
•Successful technical proof of concept regarding continuous antibody processing.•Fully automated and closed pilot plant and 100% single-use equipment.•Continuously operated platform process.•Pilot ...plant’s bulk drug substance fulfills specification limits.
To maintain or strengthen their market position, biopharmaceutical producers have to adapt their production facilities to a drastically changed market environment. Contrary to currently used large scale batch-wise operated production facilities, where stainless steel equipment is widely applied, small scale and flexible production processes are desired. Consequently, the concept of the “biofacility of the future” has been developed, which combines the attributes fast, flexible, small, inexpensive and sustainable. Four design principles build the facility’s basis and are presented within this work: continuous processing, 100% single-use equipment, closed processing and adopting the ballroom concept. However, no publication presents a completely continuously operated platform process for the production of monoclonal antibodies up to now. Therefore, this work establishes the proof of concept regarding continuous antibody manufacturing. A pilot plant for the production of monoclonal antibodies has been built 100% in single-use equipment. It was operated fully continuous and automated in the upstream and the downstream part. The concepts that allow continuously operating the pilot plant are presented within this work, i.e., continuously operated filtration, continuously operated viral inactivation, continuously operated chromatography and a continuously operated formulation. Analytics showed that the produced product was within specification limits of industrial bulk drug substances.
Quantum information processing (QIP) could revolutionize areas ranging from chemical modeling to cryptography. One key figure of merit for the smallest unit for QIP, the qubit, is the coherence time ...(T 2), which establishes the lifetime for the qubit. Transition metal complexes offer tremendous potential as tunable qubits, yet their development is hampered by the absence of synthetic design principles to achieve a long T 2. We harnessed molecular design to create a series of qubits, (Ph4P)2V(C8S8)3 (1), (Ph4P)2V(β-C3S5)3 (2), (Ph4P)2V(α-C3S5)3 (3), and (Ph4P)2V(C3S4O)3 (4), with T 2s of 1–4 μs at 80 K in protiated and deuterated environments. Crucially, through chemical tuning of nuclear spin content in the vanadium(IV) environment we realized a T 2 of ∼1 ms for the species (d 20-Ph4P)2V(C8S8)3 (1′) in CS2, a value that surpasses the coordination complex record by an order of magnitude. This value even eclipses some prominent solid-state qubits. Electrochemical and continuous wave electron paramagnetic resonance (EPR) data reveal variation in the electronic influence of the ligands on the metal ion across 1–4. However, pulsed measurements indicate that the most important influence on decoherence is nuclear spins in the protiated and deuterated solvents utilized herein. Our results illuminate a path forward in synthetic design principles, which should unite CS2 solubility with nuclear spin free ligand fields to develop a new generation of molecular qubits.
Due to their exceptional high energy density, lithium-ion batteries are of central importance in many modern electrical devices. A serious limitation, however, is the slow charging rate used to ...obtain the full capacity. Thus far, there have been no ways to increase the charging rate without losses in energy density and electrochemical performance. Here we show that the charging rate of a cathode can be dramatically increased via interaction with white light. We find that a direct exposure of light to an operating LiMn
O
cathode during charging leads to a remarkable lowering of the battery charging time by a factor of two or more. This enhancement is enabled by the induction of a microsecond long-lived charge separated state, consisting of Mn
(hole) plus electron. This results in more oxidized metal centers and ejected lithium ions are created under light and with voltage bias. We anticipate that this discovery could pave the way to the development of new fast recharging battery technologies.
Let
k
be a field of characteristic
p
. We introduce a formalism of mixed sheaves with coefficients in
k
and apply it in representation theory. We construct a system of
k
-linear triangulated category ...of motives on schemes over
F
¯
p
, which has a six functor formalism and computes higher Chow groups. Indeed, it behaves similarly to other categories of mixed sheaves that one is used to. We attempt to make its construction also accessible to non-experts. Next, we consider the subcategory of
stratified mixed Tate motives
defined for affinely stratified varieties, discuss perverse and parity motives and prove formality results. We combine this with results of Soergel to construct a geometric and graded version of the derived
modular category
O
(
G
)
, consisting of rational representations of a semisimple algebraic group
G
/
k
.
The photoexcited triplet state of the “primary donors” in the two photosystems of oxygenic photosynthesis has been investigated by means of electron-nuclear double resonance (ENDOR) at Q-band ...(34 GHz). The data obtained represent the first set of
1
H hyperfine coupling tensors of the
3
P700 triplet state in PSI and expand the existing data set for
3
P680. We achieved an extensive assignment of the observed electron-nuclear hyperfine coupling constants (hfcs) corresponding to the methine α-protons and the methyl group β-protons of the chlorophyll (Chl) macrocycle. The data clearly confirm that in both photosystems the primary donor triplet is located on one specific monomeric Chl at cryogenic temperature. In comparison to previous transient ENDOR and pulse ENDOR experiments at standard X-band (9–10 GHz), the pulse Q-band ENDOR spectra demonstrate both improved signal-to-noise ratio and increased resolution. The observed ENDOR spectra for
3
P700 and
3
P680 differ in terms of the intensity loss of lines from specific methyl group protons, which is explained by hindered methyl group rotation produced by binding site effects. Contact analysis of the methyl groups in the PSI crystal structure in combination with the ENDOR analysis of
3
P700 suggests that the triplet is located on the Chl
a
ʹ (P
A
) in PSI. The results also provide additional evidence for the localization of
3
P680 on the accessory Chl
D1
in PSII.
Ultrafast photoinduced electron transfer (PIET) dynamics of a C70-encapsulated bisporphyrin covalent organic polyhedron hybrid (C70@COP-5) is studied in a nonpolar toluene medium with fluorescence ...and transient absorption spectroscopies. This structurally rigid donor (D)–acceptor (A) molecular hybrid offers a new platform featuring conformationally predetermined cofacial D–A orientation with a fixed edge-to-edge separation, R EE (2.8 Å), without the aid of covalent bonds. Sub-picosecond PIET (τET ≤ 0.4 ps) and very slow charge recombination (τCR ≈ 600 ps) dynamics are observed. The origin of these dynamics is discussed in terms of enhanced D–A coupling (V = 675 cm–1) and extremely small reorganization energy (λ ≈ 0.18 eV), induced by the intrinsic structural rigidity of the C70@COP-5 complex.
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