1,696 research outputs found
Twirling and Hamiltonian engineering via dynamical decoupling for Gottesman-Kitaev-Preskill quantum computing
I introduce an energy constrained approximate twirling operation that can be used to diagonalize effective logical channels in Gottesman-Kitaev-Preskill (GKP) quantum error correction, project states into the GKP code space and construct a dynamical decoupling sequence with fast displacements pulses to distill the GKP stabilizer Hamiltonians from a suitable substrate Hamiltonian. The latter is given by an LC oscillator comprising a superinductance in parallel to a Josephson Junction. This platform, in principle, allows for protected GKP quantum computing without explicit stabilizer measurements or state reset by dynamically generating a “passively” stabilized GKP qubit
The Jacob A. Riis-Theodore Roosevelt Digital Archive
The Jacob A. Riis-Theodore Roosevelt Digital Archive is a digital archive focused on the Progressive Era in US history, which lasted from the late 19th century to the early 20th century. During the Progressive Era, reformers from the American middle class made significant strides in addressing social issues in urban areas and among the working and lower classes. These social issues included tenement housing, prostitution, and other forms of corruption. Some well-known reformers include Jacob Riis, the photographer and author of How The Other Half Lives, Upton Sinclair, author of The Jungle, and Jane Addams, founder of Hull House. The digital archive is specifically focused on Riis and former US president Theodore Roosevelt, the latter of whom was the founding member of the Progressive Party. This approach presents two different ways that Progressive Reform was brought about in late 19th century America: the reformer (Riis) directly worked with people afflicted by societal issues on a daily basis and knew exactly what they were going through, whereas the politician (Roosevelt) used political power and influence to encourage his colleagues and the masses to realize America\u27s social injustices and to help quell them.
The scope of the digital archive focuses solely on the New York City area, which was one of the prime locations that experienced Progressive Reform in the United States. As such, the contents of the archive were derived from the New York Public Library and other academic digital collections. The Jacob A. Riis-Theodore Roosevelt Digital Archive will make contributions to the discipline of history by making learning about a certain period of the past more interactive and resourceful for the average, tech-savvy 21st century student. In addition, visitors to the Digital Archive will get a better sense of how a digital archive operates by exploring its layout, which includes a section for collections and a section for exhibits
The Small Stellated Dodecahedron Code and Friends
We explore a distance-3 homological CSS quantum code, namely the small
stellated dodecahedron code, for dense storage of quantum information and we
compare its performance with the distance-3 surface code. The data and ancilla
qubits of the small stellated dodecahedron code can be located on the edges
resp. vertices of a small stellated dodecahedron, making this code suitable for
3D connectivity. This code encodes 8 logical qubits into 30 physical qubits
(plus 22 ancilla qubits for parity check measurements) as compared to 1 logical
qubit into 9 physical qubits (plus 8 ancilla qubits) for the surface code. We
develop fault-tolerant parity check circuits and a decoder for this code,
allowing us to numerically assess the circuit-based pseudo-threshold.Comment: 19 pages, 14 figures, comments welcome! v2 includes updates which
conforms with the journal versio
a lattice perspective
We examine general Gottesman-Kitaev-Preskill (GKP) codes for continuous-variable quantum error correction, including concatenated GKP codes, through the lens of lattice theory, in order to better understand the structure of this class of stabilizer codes. We derive formal bounds on code parameters, show how different decoding strategies are precisely related, propose new ways to obtain GKP codes by means of glued lattices and the tensor product of lattices and point to natural resource savings that have remained hidden in recent approaches. We present general results that we illustrate through examples taken from different classes of codes, including scaled self-dual GKP codes and the concatenated surface-GKP code
Good Gottesman-Kitaev-Preskill codes from the NTRU cryptosystem
We introduce a new class of random Gottesman-Kitaev-Preskill (GKP) codes
derived from the cryptanalysis of the so-called NTRU cryptosystem. The derived
codes are good in that they exhibit constant rate and average distance scaling
with high probability, where is the number of
bosonic modes, which is a distance scaling equivalent to that of a GKP code
obtained by concatenating single mode GKP codes into a qubit-quantum error
correcting code with linear distance. The derived class of NTRU-GKP codes has
the additional property that decoding for a stochastic displacement noise model
is equivalent to decrypting the NTRU cryptosystem, such that every random
instance of the code naturally comes with an efficient decoder. This
construction highlights how the GKP code bridges aspects of classical error
correction, quantum error correction as well as post-quantum cryptography. We
underscore this connection by discussing the computational hardness of decoding
GKP codes and propose, as a new application, a simple public key quantum
communication protocol with security inherited from the NTRU cryptosystem.Comment: 23 pages, 10 figures, comments welcome! Version 2 has minor
correction
Latte: Lightweight Aliasing Tracking for Java
Many existing systems track aliasing and uniqueness, each with their own
trade-off between expressiveness and developer effort. We propose Latte, a new
approach that aims to minimize both the amount of annotations and the
complexity of invariants necessary for reasoning about aliasing in an
object-oriented language with mutation. Our approach only requires annotations
for parameters and fields, while annotations for local variables are inferred.
Furthermore, it relaxes uniqueness to allow aliasing among local variables, as
long as this aliasing can be precisely determined. This enables support for
destructive reads without changes to the language or its run-time semantics.
Despite this simplicity, we show how this design can still be used for tracking
uniqueness and aliasing in a local sequential setting, with practical
applications, such as modeling a stack
A sizing and vehicle matching methodology for boundary layer ingesting propulsion systems
Boundary layer ingesting (BLI) propulsion systems offer potential fuel burn reduction for civil aviation and synergize with new advanced airframe concepts. However, the distorted inlet flow for BLI systems can cause performance and stability margin loss. System level analyses generally size a single engine at a fixed design point which ignores the distributed nature of many BLI architectures. Furthermore, operability and performance during o design are generally not considered during the sizing process. In this thesis, a methodology is developed for multi-design point sizing of BLI propulsion systems for specific vehicle geometry including an operability constraint. The methodology is applied to a 300 passenger hybrid-wing body vehicle with embedded turbofan engines.
The methodology required investigations into three main areas of research. The first was the modeling of BLI impacts over a range of flight conditions. A BLI analysis tool was developed which models the vehicle boundary layer, pre-entry region, inlet, and fan losses throughout the entire flight envelope. An experiment investigating the impact of the modeling approach is conducted, and results show that proper mapping of the fan, inlet, and BLI propulsive benefit is crucially important for making proper design decisions. The impact of BLI on the system was found to vary significantly during o ff design and especially with changes in vehicle angle of attack. The operability constraint is investigated using a parallel compressor model and was found to place a minimum limit on the propulsor height.
The second area of investigation was the creation of a multi-propulsor sizing methodology which accounts for diff erences between propulsors during
flight that is induced by their interaction with the vehicle. A modified multi-design point approach was used which employs a set of design and power management rules to relate the operation of the propulsors. A performance comparison of this methodology with the standard single propulsor approach showed a signicant difference.
The final area of investigation was the determination of critical o ff-design conditions for the sizing procedure. A screening process is developed which tests all off -design conditions for a subset of the design space to find conditions which are stall margin or thrust deficient. The experiment showed that it is necessary to consider the high angle of attack take-off condition during sizing for the HWB vehicle and that a variable area nozzle is required to meet the operability constraint. A follow on experiment showed that the inclusion of this point reduced the achievable fuel burn benefit for more aggressive BLI designs.Boundary layer ingesting (BLI) propulsion systems offer potential fuel burn reduction for civil aviation and synergize with new advanced airframe concepts. However, the distorted inlet flow for BLI systems can cause performance and stability margin loss. System level analyses generally size a single engine at a fixed design point which ignores the distributed nature of many BLI architectures. Furthermore, operability and performance during o design are generally not considered during the sizing process. In this thesis, a methodology is developed for multi-design point sizing of BLI propulsion systems for specific vehicle geometry including an operability constraint. The methodology is applied to a 300 passenger hybrid-wing body vehicle with embedded turbofan engines.
The methodology required investigations into three main areas of research. The first was the modeling of BLI impacts over a range of flight conditions. A BLI analysis tool was developed which models the vehicle boundary layer, pre-entry region, inlet, and fan losses throughout the entire flight envelope. An experiment investigating the impact of the modeling approach is conducted, and results show that proper mapping of the fan, inlet, and BLI propulsive benefit is crucially important for making proper design decisions. The impact of BLI on the system was found to vary significantly during o ff design and especially with changes in vehicle angle of attack. The operability constraint is investigated using a parallel compressor model and was found to place a minimum limit on the propulsor height.
The second area of investigation was the creation of a multi-propulsor sizing methodology which accounts for diff erences between propulsors during
flight that is induced by their interaction with the vehicle. A modified multi-design point approach was used which employs a set of design and power management rules to relate the operation of the propulsors. A performance comparison of this methodology with the standard single propulsor approach showed a signicant difference.
The final area of investigation was the determination of critical o ff-design conditions for the sizing procedure. A screening process is developed which tests all off -design conditions for a subset of the design space to find conditions which are stall margin or thrust deficient. The experiment showed that it is necessary to consider the high angle of attack take-off condition during sizing for the HWB vehicle and that a variable area nozzle is required to meet the operability constraint. A follow on experiment showed that the inclusion of this point reduced the achievable fuel burn benefit for more aggressive BLI designs.Ph.D
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