Over the past several decades, a rich series of experiments has repeatedly verified the quantum nature of superconducting devices, leading some of these systems to be regarded as artificial atoms. In addition to their application in quantum information processing, these ‘atoms’ provide a test bed for studying quantum mechanics in macroscopic limits. Regarding the last point, we present here a feasible protocol for directly testing time reversal symmetry (TRS) through the verification of the microreversibility principle in a superconducting artificial atom. TRS is a fundamental property of quantum mechanics and is expected to hold if the dynamics of the artificial atom strictly follow the Schrödinger equation. However, this property has yet to be tested in any macroscopic quantum system. In the end, as an application of this work, we outline how the successful implementation of the protocol would provide the first verification of the quantum work fluctuation theorems with superconducting systems.
Over the past several decades, a rich series of experiments has repeatedly verified the quantum nature of superconducting devices, leading some of these systems to be regarded as artificial atoms. In addition to their application in quantum information processing, these ‘atoms’ provide a test bed for studying quantum mechanics in macroscopic limits. Regarding the last point, we present here a feasible protocol for directly testing time reversal symmetry (TRS) through the verification of the microreversibility principle in a superconducting artificial atom. TRS is a fundamental property of quantum mechanics and is expected to hold if the dynamics of the artificial atom strictly follow the Schrödinger equation. However, this property has yet to be tested in any macroscopic quantum system. In the end, as an application of this work, we outline how the successful implementation of the protocol would provide the first verification of the quantum work fluctuation theorems with superconducting systems.
Over the past several decades, a rich series of experiments has repeatedly verified the quantum nature of superconducting devices, leading some of these systems to be regarded as artificial atoms. In addition to their application in quantum information processing, these 'atoms' provide a test bed for studying quantum mechanics in macroscopic limits. Regarding the last point, we present here a feasible protocol for directly testing time reversal symmetry (TRS) through the verification of the microreversibility principle in a superconducting artificial atom. TRS is a fundamental property of quantum mechanics and is expected to hold if the dynamics of the artificial atom strictly follow the Schrödinger equation. However, this property has yet to be tested in any macroscopic quantum system. In the end, as an application of this work, we outline how the successful implementation of the protocol would provide the first verification of the quantum work fluctuation theorems with superconducting systems.
Superconducting quantum circuits are promising systems for experiments testing fundamental quantum mechanics on a macroscopic scale and for applications in quantum information processing. We report on the fabrication and characterization of superconducting flux qubits, readout dc SQUIDs, on-chip shunting capacitors, and high-quality coplanar waveguide resonators. Furthermore, we discuss the tunability and fundamental symmetry aspects inherent to all superconducting qubits, which can be regarded as artificial solid-state atoms. Comparing them to their natural counterparts, we discuss first- and second-order energy shifts due to static control fields. Additionally, we present an intuitive derivation of the first- and second-order matrix elements for level transitions in the presence of coherent microwave driving.
In this paper, we investigate the application of Time-Reversal Symmetry (TRS) in Quantum Wireless Sensor Networks (QWSNs) to enhance communication performance. QWSNs combine quantum communication principles with traditional wireless sensor network technologies, offering the potential for improved security, energy efficiency, and signal quality. TRS, a concept from signal processing and quantum mechanics, focuses transmitted signals back toward the receiver, compensating for noise, interference, and fading effects. By applying TRS to QWSNs, we aim to optimize throughput, reduce latency, and enhance energy efficiency in challenging communication environments. The paper presents a theoretical framework for integrating TRS into QWSNs, including mathematical formulations for its impact on key network performance metrics. We also consider real-world channel models, such as Rayleigh and Rician fading, along with network interference, to demonstrate how TRS can improve communication in practical settings. The discussion extends to the broader potential of TRS in quantum communication systems, particularly in **Quantum Key Distribution (QKD)**, **quantum entanglement**, and **quantum networking** applications. The findings highlight TRS as a promising approach to optimize quantum communication in sensor networks and provide a foundation for future research in the intersection of quantum technologies and wireless networks.
The purpose -of this work is to discuss the symmetry, or lack of it, under reversal of motion in physical objects, states and processes. Considerations of such symmetry are made in both classical and quantum physics, notably in the problem of reconciling the assumed time-reversal symmetry of microscopic processes with the observed asymmetry of macroscopic processes. In the case of classical mechanics, a simple model of a free particle colliding with a series of almost stationary or stationary particles of smaller mass is introduced in order to show how a friction-like phenomenon can arise from processes all of which have symmetry under reversal of motion. It is maintained throughout that symmetry under reversal of motion is a property of all fundamental states and processes in nature.
This paper proposes two precise, platform-independent experiments that aim to test the foundational assumptions of quantum mechanics: namely, whether time-reversal symmetry holds exactly at the quantum level, and whether quantum measurements truly erase all information about unrealized possibilities. While inspired by larger theoretical ideas of generative wholeness, the experiments are intentionally designed in a model-agnostic way and can be implemented with current technologies such as trapped ions, superconducting qubits, or advanced photonic systems. The first experiment compares the statistical outcomes of a quantum system measured in one order with those when the same measurements are applied in reverse order. Under standard theory, no irreducible asymmetry should remain after all known disturbances are controlled. Detecting a residual asymmetry would signal a fundamental microscopic arrow of time. The second experiment examines whether a quantum system retains an intrinsic “memory” of measurements that were performed but whose results were ignored or not recorded. By comparing two sequences, one where an intermediate measurement is omitted entirely and another where it is performed but discarded, the design tests for subtle deviations from the standard projection rule. A confirmed deviation would indicate non-Markovian, intrinsic memory effects in quantum measurement itself. Both proposals are framed as “null tests”: if the orthodox theory is complete, the results should vanish within error bars. Any non-zero finding would open a doorway to new physics, probing the nature of time, measurement, and possibility in the quantum domain. Keywords: time asymmetry, projection postulate, quantum measurement, sequential measurements, intrinsic memory, non-Markovianity, trapped ions, superconducting qubits, photonics, foundational tests of quantum mechanics.
Superconducting quantum devices have drawn the attention of physicists greatly in recent years, not only because they are one of the most favorable candidates for developing a solid state quantum computer, but also because they can be employed as test systems for understanding quantum mechanics at nearly macro scale. Superconducting quantum devices can be divided into two groups: the superconducting resonators (linear devices), which have equally spaced discrete energy levels, and the artificial atoms (non-linear devices) consisting of Josephson junctions which have unequally spaced discrete energy levels. By combining these two kinds of devices together, a solid state counterpart of optical cavity quantum electrodynamics (QED) known as circuit QED emerges. Experiments of cavity QED and quantum optics can be reproduced in either circuit QED systems or in bare superconducting artificial atoms. As an example, we have observed the Autler-Townes effect in a three-level artificial atom called phase qutrit. \nMore than one decade has passed since the first experimental demonstration of superconducting two-level artificial atom (qubit). However, to build a practical quantum computer with thousands of superconducting qubits there is still a long way to go (we are at the stage of three qubits now). One of the main obstacles preventing us from scaling up a superconducting quantum computer, as well as some other kinds of quantum computers, has been decoherence, which is believed to be dominated by the low frequency noise due to the two-level system (TLS) fluctuators located inside the Josephson junction barrier. We have experimentally simulated the dynamics of a qubit longitudinally coupled to a randomly fluctuating TLS. A phenomenon known as motional averaging has been observed. \nIn this thesis, theoretical models for decoherence in both resonator and artificial atoms have been established and used for explaining phenomena observed in the experiments performed in our laboratory. The phenomenon of decoherence in coupled bipartite systems has been also studied, and besides the already known entanglement sudden death phenomenon, stable entanglement (robust under decoherence) generated from an arbitrary initial state has been found in these systems.