3,119 research outputs found
Floquet engineering from long-range to short-range interactions
Quantum simulators based on atoms or molecules often have long-range
interactions due to dipolar or Coulomb interactions. We present a method based
on Floquet engineering to turn a long-range interaction into a short-range one.
By modulating a magnetic-field gradient with one or a few frequencies, one
reshapes the interaction profile, such that the system behaves as if it only
had nearest-neighbor interactions. Our approach works in both one and two
dimensions and for both spin-1/2 and spin-1 systems. It does not require
individual addressing, and is applicable to all experimental systems with
long-range interactions: trapped ions, polar molecules, Rydberg atoms,
nitrogen-vacancy centers, and cavity QED. Our approach allows one achieve a
short-range interaction without relying on Hubbard superexchange.Comment: 6 pages, 5 figure
The Fundi Effect: Activism through Empowerment
The participatory democracy strategy of organization used by Ella Baker was greatly productive in grassroots activism, and has the potential to strengthen the political struggles of the present to the height of the movements in times past. Ella Baker was a prominent figure in the black freedom struggle. She was active in fighting for equal rights for Afrikans in America for over five decades. Her approach was characterized by an ability to mobilize and influence youth to action. In this work, there will be an analytical examination of how this methodology is equipped to stand the tests of time through what will be called The Fundi Effect. The Fundi Effect is a method of activism that is capable of being applied inter-generationally, and has the ability to address the reactionary manner with which injustice is dealt in attempts at social movements at present. Keywords: Ella Baker, civil rights movement, The Fundi Effect, youth activism, grassroots organizatio
Crosstalk-free Conjugate Networks for Optical Multicast Switching
High-speed photonic switching networks can switch optical signals at the rate
of several terabits per second. However, they suffer from an intrinsic
crosstalk problem when two optical signals cross at the same switch element. To
avoid crosstalk, active connections must be node-disjoint in the switching
network. In this paper, we propose a sequence of decomposition and merge
operations, called conjugate transformation, performed on each switch element
to tackle this problem. The network resulting from this transformation is
called conjugate network. By using the numbering-schemes of networks, we prove
that if the route assignments in the original network are link-disjoint, their
corresponding ones in the conjugate network would be node-disjoint. Thus,
traditional nonblocking switching networks can be transformed into
crosstalk-free optical switches in a routine manner. Furthermore, we show that
crosstalk-free multicast switches can also be obtained from existing
nonblocking multicast switches via the same conjugate transformation.Comment: 10 page
Pattern formation of quantum jumps with Rydberg atoms
We study the nonequilibrium dynamics of quantum jumps in a one-dimensional chain of atoms. Each atom is driven on a strong transition to a short-lived state and on a weak transition to a metastable state. We choose the metastable state to be a Rydberg state so that when an atom jumps to the Rydberg state, it inhibits or enhances jumps in the neighboring atoms. This leads to rich spatiotemporal dynamics that are visible in the fluorescence of the strong transition. It also allows one to dissipatively prepare Rydberg crystals
Heralded magnetism in non-Hermitian atomic systems
Quantum phase transitions are usually studied in terms of Hermitian
Hamiltonians. However, cold-atom experiments are intrinsically non-Hermitian
due to spontaneous decay. Here, we show that non-Hermitian systems exhibit
quantum phase transitions that are beyond the paradigm of Hermitian physics. We
consider the non-Hermitian XY model, which can be implemented using three-level
atoms with spontaneous decay. We exactly solve the model in one dimension and
show that there is a quantum phase transition from short-range order to
quasi-long-range order despite the absence of a continuous symmetry in the
Hamiltonian. The ordered phase has a frustrated spin pattern. The critical
exponent can be 1 or 1/2. Our results can be seen experimentally with
trapped ions, cavity QED, and atoms in optical lattices.Comment: 7 pages + appendi
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