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Spacetime diamonds

MetadataDetails
Publication Date2016-02-09
JournalPhysical review. D/Physical review. D.
AuthorsDaiqin Su, Timothy C. Ralph
InstitutionsCentre for Quantum Computation and Communication Technology, The University of Queensland
Citations17
AnalysisFull AI Review Included

Technical Documentation & Analysis: Spacetime Diamonds

Section titled “Technical Documentation & Analysis: Spacetime Diamonds”

This document analyzes the research paper “Spacetime diamonds” (arXiv:1507.00423v2) to highlight the material requirements necessary for experimental realization and connects these needs directly to 6CCVD’s advanced MPCVD diamond capabilities.


The research establishes a theoretical framework for detecting thermal radiation analogous to the Unruh effect, localized within a finite spacetime region (“diamond”). The findings have direct implications for high-precision quantum sensing and integrated quantum systems, areas where 6CCVD’s specialized diamond materials are critical enablers.

  • Thermal Radiation Confirmation: The particle-number distribution of diamond modes in the Minkowski vacuum is proven to be thermal, confirming a detectable analogue of the Unruh effect.
  • Diamond Temperature ($T_D$): The temperature is inversely proportional to the observer’s finite lifetime ($T$), given by $T_D = 2 / (\pi T)$.
  • Detection Mechanism: $T_D$ is detectable using an inertial Unruh-DeWitt detector with a specific energy scaling factor, which requires precise control over the detector’s Hamiltonian.
  • Experimental Feasibility: The paper identifies “artificial atoms such as the superconducting qubits and quantum dots” as the most promising candidates for realizing the energy-scaled detector.
  • Material Requirement: Experimental realization demands ultra-high purity, low-defect host materials suitable for integrated quantum devices, making MPCVD Single Crystal Diamond (SCD) the ideal platform.
  • Entanglement Dominance: Timelike entanglement between adjacent spacetime diamonds is shown to be dominant, suggesting potential for quantum information experiments based on relativistic effects.

The following table summarizes the key quantifiable parameters derived from the theoretical analysis, relevant for designing the required quantum detection platform.

ParameterValueUnitContext
Diamond Temperature ($T_D$)$2 / (\pi T)$N/AInversely proportional to the observer’s lifetime $T$.
Estimated Detectable $T_D$$\sim 1$KCorresponds to a required lifetime $T$ of $\sim 10^{-11}$ s.
Required Detector Lifetime ($T$)$\sim 10^{-11}$sChallenging but potentially accessible for experimental detection.
Spacetime Dimension Analyzed(1+1)N/ATheoretical calculation dimension; generalization to (1+3) is proposed.
Entanglement Condition ($\phi=0$)$(\Delta X_{10})^{2} < 1$N/AVariance of quadratures for adjacent Gaussian modes, indicating entanglement.
Correlation Decay Rate$\sim 1 / n^{2}$N/AAsymptotic decay of correlation between non-adjacent diamonds (large $n$).
Detector Hamiltonian Scaling$H_0 / (1 - a^{2} t^{2} / 4)$N/ARequired time-dependent scaling for the inertial detector.

The theoretical results rely on advanced techniques in relativistic quantum field theory and quantum optics modeling.

  1. Coordinate Transformation: A new coordinate system ($\eta, \xi, \zeta, \rho$), called diamond coordinates, was introduced to describe spacetime events and field modes localized within the finite diamond region.
  2. Bogoliubov Transformation: The Bogoliubov transformation coefficients were calculated between the diamond modes and the standard Minkowski plane wave modes to determine the particle-number distribution.
  3. Thermal Distribution Derivation: The particle-number distribution was shown to be exactly thermal, yielding the Diamond Temperature ($T_D$).
  4. Energy-Scaled Detector Model: An inertial Unruh-DeWitt detector model was proposed, incorporating a time-dependent energy scaling factor to restrict the detector’s effective lifetime to the diamond region.
  5. Gaussian Formalism for Entanglement: Localized Gaussian wave packet modes were constructed in each diamond to analyze timelike entanglement between adjacent and distant diamonds, calculating quadrature variances.

The experimental realization of the energy-scaled detector requires a robust, high-quality material platform capable of hosting integrated quantum systems (qubits or quantum dots) and supporting complex metalization schemes for external field control. 6CCVD is uniquely positioned to supply the necessary MPCVD diamond materials.

Research Requirement6CCVD Material SolutionCustomization Potential & Advantage
Host for Artificial Atoms/Qubits (e.g., NV centers, SiV centers)Optical Grade Single Crystal Diamond (SCD)Essential for long coherence times ($T_2$). 6CCVD provides SCD with ultra-low nitrogen concentration (N < 1 ppb) and controlled defect incorporation for specific quantum emitters.
Integrated Detector FabricationCustom Dimensions & PolishingSCD plates available up to 500”m thickness. Polishing to Ra < 1nm ensures atomically smooth surfaces critical for lithography and integration of superconducting qubits or quantum dots.
Time-Dependent Energy Scaling (External E/B fields)Internal Metalization ServicesWe offer custom deposition of Au, Pt, Ti, W, Pd, or Cu contact pads and circuit traces directly onto the diamond surface, enabling the application of the required time-dependent external electric or magnetic fields.
Generalization to (1+3) SpacetimeThick Substrates & Large Area PCDSCD substrates available up to 10mm thickness for bulk experiments. PCD wafers up to 125mm diameter for large-scale integration and network studies.
High-Density Quantum Networks (Correlations between diamonds)Heavy Boron-Doped Diamond (BDD)BDD material can be used as a conductive layer or electrode in complex integrated quantum devices, offering precise control over local electric potentials and charge states near quantum emitters.

The successful transition from the theoretical (1+1)-dimensional model to a physically relevant (1+3)-dimensional experiment requires expert material selection and fabrication planning. 6CCVD’s in-house PhD team specializes in optimizing diamond properties (purity, orientation, surface termination) for complex quantum sensing and integrated quantum optics projects, such as those involving the detection of the Diamond Temperature ($T_D$).

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

We show that the particle-number distribution of diamond modes, modes that\nare localized in a finite space-time region, are thermal for the Minkowski\nvacuum state of a massless scalar field, an analogue to the Unruh effect. The\ntemperature of the diamond is inversely proportional to its size. An inertial\nobserver can detect this thermal radiation by coupling to the diamond modes\nusing an appropriate energy-scaled detector. We further investigate the\ncorrelations between various diamonds and find that entanglement between\nadjacent diamonds dominates.\n

  1. 1984 - Quantum Fields in Curved Space
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