Recursos de colección
Caltech Authors (160.918 recursos)
Repository of works by Caltech published authors.
Group = Walter Burke Institute for Theoretical Physics
Repository of works by Caltech published authors.
Group = Walter Burke Institute for Theoretical Physics
Marks, Jacob; Jochym-O’Connor, Tomas; Gheorghiu, Vlad
We introduce and analyze a new type of decoding algorithm called general color clustering, based on renormalization group methods, to be used in qudit color codes. The performance of this decoder is analyzed under a generalized bit-flip error model, and is used to obtain the first memory threshold estimates for qudit 6-6-6 color codes. The proposed decoder is compared with similar decoding schemes for qudit surface codes as well as the current leading qubit decoders for both sets of codes. We find that, as with surface codes, clustering performs sub-optimally for qubit color codes, giving a threshold of 5.6% compared...
Lippuner, Jonas; Fernández, Rodrigo; Roberts, Luke F.; Foucart, Francois; Kasen, Daniel; Metzger, Brian D.; Ott, Christian D.
We investigate the nucleosynthesis of heavy elements in the winds ejected by accretion discs formed in neutron star mergers. We compute the element formation in disc outflows from hypermassive neutron star (HMNS) remnants of variable lifetime, including the effect of angular momentum transport in the disc evolution. We employ long-term axisymmetric hydrodynamic disc simulations to model the ejecta, and compute r-process nucleosynthesis with tracer particles using a nuclear reaction network containing ∼8000 species. We find that the previously known strong correlation between HMNS lifetime, ejected mass and average electron fraction in the outflow is directly related to the amount of...
Bao, Ning; Bousso, Raphael; Jordan, Stephen; Lackey, Brad
Denef and Douglas have observed that in certain landscape models the problem of finding small values of the cosmological constant is a large instance of a problem that is hard for the complexity class NP (Nondeterministic Polynomial-time). The number of elementary operations (quantum gates) needed to solve this problem by brute force search exceeds the estimated computational capacity of the observable Universe. Here we describe a way out of this puzzling circumstance: despite being NP-hard, the problem of finding a small cosmological constant can be attacked by more sophisticated algorithms whose performance vastly exceeds brute force search. In fact, in...
Cecotti, Sergio; Song, Jaewon; Vafa, Cumrun; Yan, Wenbin
We show that specializations of the 4d N=2 superconformal index labeled by an integer N is given by Tr ℳ^N where ℳ is the Kontsevich-Soibelman monodromy operator for BPS states on the Coulomb branch. We provide evidence that the states enumerated by these limits of the index lead to a family of 2d chiral algebras ANAN. This generalizes the recent results for the N = −1 case which corresponds to the Schur limit of the superconformal index. We show that this specialization of the index leads to the same integrand as that of the elliptic genus of compactification of the...
Cotler, Jordan; Hunter-Jones, Nicholas; Liu, Junyu; Yoshida, Beni
Chaos and complexity entail an entropic and computational obstruction to describing a system, and thus are intrinsically difficult to characterize. In this paper, we consider time evolution by Gaussian Unitary Ensemble (GUE)
Hamiltonians and analytically compute out-of-time-ordered correlation functions (OTOCs) and frame potentials to quantify scrambling, Haar-randomness, and circuit complexity. While our random matrix analysis gives a qualitatively correct prediction of the late-time behavior of chaotic systems, we find unphysical behavior at early times including an $\mathcal{O}(1)$ scrambling
time and the apparent breakdown of spatial and temporal locality. The salient feature of GUE Hamiltonians which gives us computational traction is the Haar-invariance...
Cotler, Jordan; Hunter-Jones, Nicholas; Liu, Junyu; Yoshida, Beni
Chaos and complexity entail an entropic and computational obstruction to describing a system, and thus are intrinsically difficult to characterize. In this paper, we consider time evolution by Gaussian Unitary Ensemble (GUE)
Hamiltonians and analytically compute out-of-time-ordered correlation functions (OTOCs) and frame potentials to quantify scrambling, Haar-randomness, and circuit complexity. While our random matrix analysis gives a qualitatively correct prediction of the late-time behavior of chaotic systems, we find unphysical behavior at early times including an $\mathcal{O}(1)$ scrambling
time and the apparent breakdown of spatial and temporal locality. The salient feature of GUE Hamiltonians which gives us computational traction is the Haar-invariance...
Cotler, Jordan; Hunter-Jones, Nicholas; Liu, Junyu; Yoshida, Beni
Chaos and complexity entail an entropic and computational obstruction to describing a system, and thus are intrinsically difficult to characterize. In this paper, we consider time evolution by Gaussian Unitary Ensemble (GUE) Hamiltonians and analytically compute out-of-time-ordered correlation functions (OTOCs) and frame potentials to quantify scrambling, Haar-randomness, and circuit complexity. While our random matrix analysis gives a qualitatively correct prediction of the late-time behavior of chaotic systems, we find unphysical behavior at early times including an O(1) scrambling time and the apparent breakdown of spatial and temporal locality. The salient feature of GUE Hamiltonians which gives us computational traction is...
Maia, Natália T.; Galley, Chad R.; Leibovich, Adam K.; Porto, Rafael A.
We compute the leading post-Newtonian (PN) contributions at quadratic order in the spins to the radiation-reaction acceleration and spin evolution for binary systems, entering at four-and-a-half PN order. Our calculation includes the backreaction from finite-size spin effects, which is presented for the first time. The computation is carried out, from first principles, using the effective field theory framework for spinning extended objects. At this order, nonconservative effects in the spin-spin sector are independent of the spin supplementary conditions. A nontrivial consistency check is performed by showing that the energy loss induced by the resulting radiation-reaction force is equivalent to the...
Maia, Natália T.; Galley, Chad R.; Leibovich, Adam K.; Porto, Rafael A.
We compute the leading post-Newtonian (PN) contributions at linear order in the spin to the radiation-reaction acceleration and spin evolution for binary systems, which enter at fourth PN order. The calculation is carried out, from first principles, using the effective field theory framework for spinning compact objects, in both the Newton-Wigner and covariant spin supplementary conditions. A nontrivial consistency check is performed on our results by showing that the energy loss induced by the resulting radiation-reaction force is equivalent to the total emitted power in the far zone, up to so-called “Schott terms.” We also find that, at this order,...
Fluder, Martin
In this paper, we initiate the study of holographic renormalization group
flows acting on the metric of four-manifolds. In particular, we derive a set of
equations which govern the evolution of a generic K\"ahler four-manifold along
the renormalization group flow in seven-dimensional gauged supergravity. The
physical eleven-dimensional M-theory setup is given by a stack of M5-branes
wrapping a calibrated K\"ahler four-cycle inside a Calabi-Yau threefold. By
topologically twisting the theory in the ultraviolet, we may choose an
arbitrary K\"ahler metric on the four-cycle as an asymptotic boundary
condition. Along the renormalization group flow, the metric moduli are largely
washed out, and at the infrared fixed point we will reach...
Chang, Chi-Ming; Fluder, Martin; Lin, Ying-Hsuan; Wang, Yifan
We combine supersymmetric localization and the conformal bootstrap to study
five-dimensional superconformal field theories. To begin, we classify the
admissible counter-terms and derive a general relation between the five-sphere
partition function and the conformal and flavor central charges. Along the way,
we discover a new superconformal anomaly in five dimensions. We then propose a
precise triple factorization formula for the five-sphere partition function,
that incorporates instantons and is consistent with flavor symmetry
enhancement. We numerically evaluate the central charges for the rank-one
Seiberg and Morrison-Seiberg theories, and find strong evidence for their
saturation of bootstrap bounds, thereby determining the spectra of long
multiplets in these theories. Lastly, our results provide...
Hellerman, Simeon; Maeda, Shunsuke
In this note we study two point functions of Coulomb branch chiral ring elements with
large R-charge, in quantum field theories with N = 2 superconformal symmetry in four
spacetime dimensions. Focusing on the case of one-dimensional Coulomb branch, we use
the effective-field-theoretic methods of [1], to estimate the two-point correlation function
Yn ≡ |x − y|2n∆O(O(x))n(O¯(y))n�in the limit where the operator insertion On has large
total R-charge J = n∆O. We show that Yn has a nontrivial but universal asymptotic
expansion at large J , of the form Yn = J !�|NO|2π�2JJα Y˜n ,where Y˜
n approaches a constant as n → ∞, and NO is...
An, Haipeng; Pospelov, Maxim; Pradler, Josef; Ritz, Adam
If dark matter (DM) particles are lighter than a few MeV/c^2 and can scatter off electrons, their interaction within the solar interior results in a considerable hardening of the spectrum of galactic dark matter received on Earth. For a large range of the mass vs. cross section parameter space, {m_e, σ_e}, the "reflected" component of the DM flux is far more energetic than the endpoint of the ambient galactic DM energy distribution, making it detectable with existing DM detectors sensitive to an energy deposition of 10−10^3 eV. After numerically simulating the small reflected component of the DM flux, we calculate...
Wang, Zitao; Ning, Shang-Qiang; Chen, Xie
In this paper, we present an exactly solvable model for two dimensional topological superconductor with helical Majorana edge modes protected by time reversal symmetry. Our construction is based on the idea of decorated domain walls and makes use of the Kasteleyn orientation on a two dimensional lattice, which was used for the construction of the symmetry protected fermion phase with Z_2 symmetry in Ref. 1 and 2. By decorating the time reversal domain walls with spinful Majorana chains, we are able to construct a commuting projector Hamiltonian with zero correlation length ground state wave function that realizes a strongly interacting...
Hunter-Jones, Nicholas; Liu, Junyu; Zhou, Yehao
The eigenstate thermalization hypothesis is a compelling conjecture which
strives to explain the apparent thermal behavior of generic observables in
closed quantum systems. Although we are far from a complete analytic
understanding, quantum chaos is often seen as a strong indication that the
ansatz holds true. In this paper, we address the thermalization of energy
eigenstates in the Sachdev-Ye-Kitaev model, a maximally chaotic model of
strongly-interacting Majorana fermions. We numerically investigate eigenstate
thermalization for specific few-body operators in the original SYK model as
well as its $\mathcal{N}=1$ supersymmetric extension and find evidence that
these models satisfy ETH. We discuss the implications of ETH for a
gravitational dual and the quantum...
Heydeman, Matthew; Schwarz, John H.; Wen, Congkao
We present tree-level $n$-particle on-shell scattering amplitudes of various
brane theories with $16$ conserved supercharges. These include the world-volume
theory of a probe D3-brane or D5-brane in 10D Minkowski spacetime as well as a
probe M5-brane in 11D Minkowski spacetime, which describes self interactions of
an abelian tensor supermultiplet with 6D $(2,0)$ supersymmetry.
Twistor-string-like formulas are proposed for tree-level scattering amplitudes
of all multiplicities for each of these theories. The R symmetry of the
D3-brane theory is shown to be $SU(4) \times U(1)$, and the $U(1)$ factor
implies that its amplitudes are helicity conserving. Each of 6D theories
(D5-brane and M5-brane) reduces to the D3-brane theory by dimensional
reduction. As...
Bartolotta, Anthony; Ramsey-Musolf, Michael J.
We analyze next-to-leading order (NLO) corrections and uncertainties for
coherent $\mu-e$ conversion . The analysis is general but numerical results
focus on ${}^{27}\textrm{Al}$, which will be used in the Mu2E experiment. We
obtain a simple expression for the branching ratio in terms of Wilson
coefficients associated with possible physics beyond the Standard Model and a
set of model-independent parameters determined solely by Standard Model
dynamics. For scalar-mediated conversion, we find that NLO two-nucleon
contributions can significantly decrease the branching ratio, potentially
reducing the rate by as much as 50%. The pion-nucleon $\sigma$-term and quark
masses give the dominant sources of parametric uncertainty in this case. For
vector-mediated conversion, the impact...
Kato, Chinami; Nagakura, Hiroki; Furusawa, Shun; Takahashi, Koh; Umeda, Hideyuki; Yoshida, Takashi; Ishidoshiro, Koji; Yamada, Shoichi
This paper is a sequel to our 2015 paper, Kato et al., which calculated the luminosities and spectra of electron-type anti-neutrinos (ν[overbar]_e) from the progenitors of core-collapse supernovae. Expecting that the capability to detect electron-type neutrinos (ν_e) will increase dramatically with the emergence of liquid-argon detectors such as DUNE, we broaden the scope in this study to include all flavors of neutrinos emitted from the pre-bounce phase. We pick up three progenitor models of electron capture supernovae (ECSNe) and iron-core collapse supernovae (FeCCSNe). We find that the number luminosities reach ~10^(57) s^(–1) and ~10^(53) s^(–1) at maximum for ν_e and...
Martin, Ivar; Refael, Gil; Halperin, Bertrand I.
When a physical system is subjected to a strong external multi-frequency
drive, its dynamics can be conveniently represented in the multi-dimensional
Floquet lattice. The number of the Floquet lattice dimensions equals the number
of {\em irrationally}-related drive frequencies, and the evolution occurs in
response to a built-in effective "electric" field, whose components are
proportional to the corresponding drive frequencies. The mapping allows to
engineer and study temporal analogs of many real-space phenomena. Here we focus
on the specific example of a two-level system under two-frequency drive that
induces topologically nontrivial band structure in the 2D Floquet space. The
observable consequence of such construction is quantized pumping of energy
between the...
Martin, Ivar; Refael, Gil; Halperin, Bertrand
When a physical system is subjected to a strong external multifrequency drive, its dynamics can be conveniently represented in the multidimensional Floquet lattice. The number of Floquet lattice dimensions equals the number of irrationally-related drive frequencies, and the evolution occurs in response to a built-in effective “electric” field, whose components are proportional to the corresponding drive frequencies. The mapping allows us to engineer and study temporal analogs of many real-space phenomena. Here, we focus on the specific example of a two-level system under a two-frequency drive that induces topologically nontrivial band structure in the 2D Floquet space. The observable consequence...