All unital qubit channels are 44-noisy operations

We show that any unital qubit channel can be implemented by letting the input system interact unitarily with a $4$-dimensional environment in the maximally mixed state and then tracing out the environment. We also provide an example where the dimension of such an environment has to be at least $3$.Comment: 8 pages, no picture

Martin Agency Freelancer Onboarding

Onboarding new employees is a necessary but often a lengthy process at any company, but it can be especially challenging for companies like The Martin Agency. An advertising firm based in Richmond, Virginia. The nature of their work channels the need for many of their employees to be freelancers or short term contractors. At the time the project began, the process to request a new freelancer would start as a paper form submitted by a department supervisor. It would then require approval from members of different departments within agency, and the data had to be converted into an electronic form to interface with systems like payroll and Active Directory. Freelancers would sometimes complete their jobs before the onboarding process was ever completed. Our solution was to design a responsive web application that provided a familiar experience to filling out the paper form, but automatically interfaced with different systems within The Martin Agency. The agencies’ developers used mostly Microsoft technologies, so to make it as easy as possible to integrate into their current environment and transfer ownership, our application used much of the same technologies. It consisted of Microsoft’s .NET 4.5 and MVC framework, Windows, IIS, and SQL Server. The application would automatically populate form dropdowns from their Media Ocean data provider. The form submissions would then create a database entry, and post a new freelancer request to WorkFront – their workflow management software. The end result was a well-documented functional application that was deployed to The Martin Agency’s development environment.https://scholarscompass.vcu.edu/capstone/1178/thumbnail.jp

What is the probability of a thermodynamical transition?

If the second law of thermodynamics forbids a transition from one state to another, then it is still possible to make the transition happen by using a sufficient amount of work. But if we do not have access to this amount of work, can the transition happen probabilistically? In the thermodynamic limit, this probability tends to zero, but here we find that for finite-sized systems, it can be finite. We compute the maximum probability of a transition or a thermodynamical fluctuation from any initial state to any final state, and show that this maximum can be achieved for any final state which is block-diagonal in the energy eigenbasis. We also find upper and lower bounds on this transition probability, in terms of the work of transition. As a bi-product, we introduce a finite set of thermodynamical monotones related to the thermo-majorization criteria which governs state transitions, and compute the work of transition in terms of them. The trade-off between the probability of a transition, and any partial work added to aid in that transition is also considered. Our results have applications in entanglement theory, and we find the amount of entanglement required (or gained) when transforming one pure entangled state into any other.Comment: 15+6 pages, 7+1 figures V3: Added discussion on heralded probability and relation to fluctuation theorems. V2: Emphasized that X can be any state and that the achievability of our result in the full thermodynamics case, holds only when the target state is block-diagonal in the energy eigenbasi

Lentiviral vector stability and process purification based on modifications to the viral envelope

Lentiviral vectors (LV) are potent tools in delivering genetic information for vac-cines and therapeutic benefits. Bioprocessing of LV remains challenging, with vec-tor generation dependent on transient transfection methods demanding high costs which are subject to batch variability. Stable producer cell lines can be employed as alternatives to promote consistent vector generation; however, the LV envelope protein must be carefully selected, with the common envelope, VSV-G, unsuitable due to cytotoxicity. Alternative envelope proteins such as RDPro and Cocal-G have been developed and their impact in bioprocessing evaluated herein. Various unit operations were studied to make comparisons of how envelope proteins affect the bioprocessing of LV. Herein, the development of a stable pro-ducer cell line with Cocal-G envelopes are described and evaluated against existing RDPro cell lines. Following this, the performance of LVs with differing envelope proteins in filtration and chromatography was investigated. The generation of stable producer cell lines with Cocal-G envelopes indicated superinfection related instability, which was ameliorated with small drug treatment, permitting adherent culture scale up over five days, generating a total of 1.92X109 TU total. During filtration, envelope and filter chemistry was of main effect with polyvinylidene difluoride membranes and VSV-G envelopes were shown to be most effective for vector transmission irrespective of filters and envelopes. During shear characterisation, all vectors were resistant up to 106s−1 shear rate, typical of most process equipment, in the ultra-scale down shear device even in the presence of air-liquid interfaces. In the membrane shear device, losses, likely from membrane adsorption, are evident with RDPro least affected. Generally, increased disc speed improved recovery although the ratio of transducing units to vector particles de-creased. A design of experiment method for anion exchange revealed weaker inter¬action of Cocal-G enveloped LVs in QA and DEAE ligand monoliths that allowed lower salt concentration to elute (1.1 M compared to 1.3 M). Affinity chromato¬graphic purification of VSV-G vectors by small protein ligands, based on the LDL-R binding domain, captured and depleted vectors in suspension, however elution was not successful with pH decrease although incubation with bead fractions achieved approximately 55% recovery. Results demonstrated different performance of vectors across unit operations which are influenced by envelope choice. The findings reported herein should assist in the achievement of scalable and robust processes for the utilisation of lentiviral vectors

Entanglement fluctuation theorems

Pure state entanglement transformations have been thought of as irreversible, with reversible transformations generally only possible in the limit of many copies. Here, we show that reversible entanglement transformations do not require processing on the many copy level, but can instead be undertaken on individual systems, provided the amount of entanglement which is produced or consumed is allowed to fluctuate. We derive necessary and sufficient conditions for entanglement manipulations in this case. As a corollary, we derive an equation which quantifies the fluctuations of entanglement, which is formally identical to the Jarzynski fluctuation equality found in thermodynamics. One can also relate a forward entanglement transformation to its reverse process in terms of the entanglement cost of such a transformation, in a manner equivalent to the Crooks relation. We show that a strong converse theorem for entanglement transformations is formally related to the second law of thermodynamics, while the fact that the Schmidt rank of an entangled state cannot increase is related to the third law of thermodynamics. Achievability of the protocols is done by introducing an entanglement battery, a device which stores entanglement and uses an amount of entanglement that is allowed to fluctuate but with an average cost which is still optimal. This allows us to also solve the problem of partial entanglement recovery, and in fact, we show that entanglement is fully recovered. Allowing the amount of consumed entanglement to fluctuate also leads to improved and optimal entanglement dilution protocols.Comment: comments welcome, v2 published versio

The second law of quantum thermodynamics as an equality

We investigate the connection between recent results in quantum thermodynamics and fluctuation relations by adopting a fully quantum mechanical description of thermodynamics. By including a work system whose energy is allowed to fluctuate, we derive a set of equalities which all thermodynamical transitions have to satisfy. This extends the condition for maps to be Gibbs-preserving to the case of fluctuating work, providing a more general characterisation of maps commonly used in the information theoretic approach to thermodynamics. For final states, block diagonal in the energy basis, this set of equalities are necessary and sufficient conditions for a thermodynamical state transition to be possible. The conditions serves as a parent equation which can be used to derive a number of results. These include writing the second law of thermodynamics as an equality featuring a fine-grained notion of the free energy. It also yields a generalisation of the Jarzynski fluctuation theorem which holds for arbitrary initial states, and under the most general manipulations allowed by the laws of quantum mechanics. Furthermore, we show that each of these relations can be seen as the quasi-classical limit of three fully quantum identities. This allows us to consider the free energy as an operator, and allows one to obtain more general and fully quantum fluctuation relations from the information theoretic approach to quantum thermodynamics.Comment: 11+3 pages. V4: Updated to match published version. Discussion of thermo-majorization and implementing arbitary unitaries added. V3: Added funding information. V2: Expanded discussion on relation to fluctuation theorem