Related Experiment Video
Updated: May 19, 2026
11:21
Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Temperature of a decoherent oscillator with strong coupling
1CIfAR Cosmology and Gravity Program, Department of Physics, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada. unruh@physics.ubc.ca
Summary
The oscillator
Area of Science:
- Quantum thermodynamics
- Open quantum systems
- Quantum measurement
Background:
- Ohmic coupling describes interactions between quantum systems and their environment.
- Reduced density matrices can indicate non-zero effective temperatures.
- Distinguishing true thermal states from environmental effects is crucial.
Purpose of the Study:
- To investigate the discrepancy between effective and actual temperatures in an oscillator coupled to a heat bath.
- To identify the cause of non-zero effective temperatures observed in such systems.
- To differentiate true thermalization from environmental-induced decoherence.
Main Methods:
- Analyzing the reduced density matrix of a quantum oscillator.
- Employing a thermometer model to measure the oscillator's actual temperature.
- Investigating Ohmic coupling to a vacuum heat bath.
Main Results:
- The reduced density matrix indicates a non-zero temperature for the oscillator.
- A thermometer measurement reveals the oscillator's actual temperature remains zero (or the bath temperature).
- The observed non-zero effective temperature is attributed to 'false-decoherence'.
Conclusions:
- Environmental coupling can lead to a non-zero effective temperature without true thermalization.
- 'False-decoherence' arises from correlations between the oscillator and the heat bath.
- The heat bath's state is influenced by the oscillator's state, not vice-versa for true thermalization.
Related Concept Videos
01:27Atomic Spectroscopy: Effects of Temperature
Atomization, converting samples into gas-phase atoms and ions, is essential for atomic spectroscopy. The flame temperature required for atomization affects the efficiency of the atomic spectroscopic methods by increasing the atomization efficiency and the relative population of the excited and ground states.
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
01:04¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
01:30Oscillations In An LC Circuit
An idealized LC circuit of zero resistance can oscillate without any source of emf by shifting the energy stored in the circuit between the electric and magnetic fields. In such an LC circuit, if the capacitor contains a charge q before the switch is closed, then all the energy of the circuit is initially stored in the electric field of the capacitor. This energy is given by
01:11Temperature and Thermal Equilibrium
Heat and temperature are essential concepts for everyone every day. The study of heat and temperature is part of an area of physics known as thermodynamics. It is not always easy to distinguish heat and temperature.
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...
01:28The Thermodynamics of Mixing
Mixing is a fascinating phenomenon in thermodynamics, particularly when considering the Gibbs energy of a mixture at constant temperature and pressure. This energy, denoted as G, tends to decrease during spontaneous mixing processes, offering insights into the composition changes that occur.Imagine two ideal gases, initially separated in different containers, with amounts nA and nB, respectively, both at a temperature T and pressure p. The chemical potentials of these gases have their 'pure'...
01:08Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...