Spacetime Foam

In his paper “Spacetime Foam, Casimir Energy and Black Hole Pair Creation” (gr-qc/9801045) and related works, Remo Garattini proposes that Casimir-like vacuum energy fluctuations at the Planck scale could enable a network of microscopic traversable wormholes between entangled black holes. He illustrates this with a “positive mass” black hole in our universe paired with a hypothetical “anti black-hole” of negative mass in a separate universe, forming a neutral pair with zero total energy via the Nariai metric and instanton processes. Building on this, a Schwarzschild kink instanton (a quantum tunneling event with no net energy) could provide a stable pathway, potentially bypassing the Nariai metric’s de Sitter background.

This suggests a reimagined scenario where, instead of a distinct negative universe, the “negative state” emerges as a localized region within our spacetime between two entangled black holes, where quantum foam induces a negative energy density through vacuum fluctuations like the Casimir effect. Aligned with the ER=EPR conjecture, this entanglement could sustain the wormhole, allowing the transfer of quantum information via qubits without structural collapse. The wormhole’s dynamic reversibility, driven by the foam’s fluctuations, might enable bidirectional data flow, creating a quantum gravitational communication network among black holes. Furthermore, if these fluctuating states could be mimicked in a laboratory using entangled quantum systems, such as superconducting circuits or optical cavities, the principles could inspire scalable quantum communication technologies, bridging cosmic and terrestrial scales.

https://www.quantamagazine.org/physicists-create-a-wormhole-using-a-quantum-computer-20221130/         A quatum computer makes a wormhole? Now in question as an increase in the Hamiltonian did not improve the picture.

Are there ways around this?

coming soon

Determining complementary properties with quantum clones

G. S. Thekkadath, R. Y. Saaltink, L. Giner, J. S. Lundeen

In a classical world, simultaneous measurements of complementary properties (e.g. position and momentum) give a system's state. In quantum mechanics, measurement-induced disturbance is largest for complementary properties and, hence, limits the precision with which such properties can be determined simultaneously. It is tempting to try to sidestep this disturbance by copying the system and measuring each complementary property on a separate copy. However, perfect copying is physically impossible in quantum mechanics. Here, we investigate using the closest quantum analog to this copying strategy, optimal cloning. The coherent portion of the generated clones' state corresponds to "twins" of the input system. Like perfect copies, both twins faithfully reproduce the properties of the input system. Unlike perfect copies, the twins are entangled. As such, a measurement on both twins is equivalent to a simultaneous measurement on the input system. For complementary observables, this joint measurement gives the system's state, just as in the classical case. We demonstrate this experimentally using polarized single photons.