Interfacing with Hardware

PyEPR has been designed to interface with a range of different EPR spectrometers, providing a hardware abstraction layer that allows users to write experiments in a hardware-agnostic manner. Currently, PyEPR supports the following hardware interfaces: - Bruker ElexSys AWG based spectrometers - ETH Zürich Matlab based homebuilt spectrometers

For homebuilt spectrometers, there can be additional packages required. Please refer to the respective hardware interface documentation for more details.

Initializing Hardware Interfaces

The hardware interfaces can be initialized by importing the respective classes from the pyepr.hardware module and providing a configuration file that specifies the hardware settings.

from pyepr.hardware.Bruker_AWG import BrukerAWG
# Initialize the Bruker AWG interface with a configuration file
interface = BrukerAWG('path/to/config_file.yaml')

from pyepr.hardware.ETH_awg import ETH_awg_interface
# Initialize the ETH Matlab interface with a configuration file
interface = ETH_awg_interface('path/to/config_file.yaml')

Configuration Files

Spectrometer:
  Type: Complete Spectrometer
  Manufacturer: Bruker
  Model: E580
  Local Name: Bruker E580

  AWG: True


  Bridge:
    Min Freq: 33 #GHz
    Max Freq: 35 #GHz
    Digital Source: False # Analogue or Digital Source (for Q-band standalone)
    d0: 650 #ns
    Sample Freq: 1 # GSa/s
    DutyCycle: 3 # Max amplifier duty cycle %
    Pulse dt: 2  #ns
    Det dt: 0.5  #ns
    Det res: 8  #bit
    Video BW: 125 #MHz on VAMP-III this changes the time base
    On Board Pcyc: False # Use on-board phase cycling generally
    On Board Pcyc (EDFS): True  # Use on-board phase cycling for EDFS experiments

Spectrometer:
  Type: Complete Spectrometer
  Manufacturer: ETH
  Model: Matlab
  Local Name: F243_AWG

  AWG: True

  Bridge:
    Min Freq: 33 #GHz
    Max Freq: 36 #GHz
    Sample Freq: 8 # GSa/s
    Det Freq: 2 #GSa/s
    Det Res: 12  #bit

  Waveform Precision: 1 #ns

Spectrometer:
  Type: Complete Spectrometer
  Manufacturer: Dummy
  Model: DummyV1
  Local Name: Dummy

  AWG: True

  Bridge:
    Min Freq: 33 #GHz
    Max Freq: 35 #GHz
    Sample Freq: 8 #GSa/s
    Det Freq: 2 #GSa/s
    Det Res: 12  #bit
  
  Dummy:
    speedup: 1000 # Default: 100
    SNR: 150
    ESEEM_depth: 0.15
    noise_level: 0.005

First Tests

After initializing the hardware interface, it is recommended to run some basic tests to ensure that the connection to the spectrometer is working correctly.

Pulse Tuning

The hardware interface can be used to create and tune pulses for the spectrometer.

Creating rectangular pulse pairs

Often we just need a pair of rectangular pulses. These can be quickly created though an amplitude sweep.

p90, p180 = interface.tune_rectpulse(
                                     tp = 16,  # Pulse length of pi/2 pulse in ns
                                     B = 12200,  # Magnetic field in Gauss
                                     freq = 34.0,  # Microwave frequency in GHz
                                     reptime = 3000,  # Repetition time in us
                                     shots = 20,  # Number of shots per point
                                     )

This will create and return a pi/2 and pi rectangular pulse tuned to the specified field and frequency. The pulses can then be used directly in sequences, and have the correct scale (amplitude) set for the hardware.

Tuning pre-defined pulse shapes

Often a specific pulse shape is required, and it is better to tune that pulse directly. This can be done using the tune_pulse method of the hardware interface. This is done as an amplitude sweep, either as a Hahn Echo (amp_hahn) or more commonly as a hole-buring recovery experiment (amp_nut). When a hole-burning recovery experiment is used, a pair of on-resonance rectangular pulses are first created using the tune_rectpulse method.

from pyepr.pulses import GaussPulse
pulse = GaussPulse(tp=32, freq=0, flipangle=np.pi)  # Create a Gaussian pulse with length 32 ns
tuned_pulse = interface.tune_pulse(
                                     pulse,
                                     'amp_nut',
                                     B = 12200,  # Magnetic field in Gauss
                                     freq = 34.0,  # Microwave frequency in GHz
                                     reptime = 3000,  # Repetition time in us
                                     shots = 20,  # Number of shots per point
                                     )