add initial version of observation capability, see #54

phetsims · Jan 4, 2025 · 8c64ef6 · 8c64ef6
1 parent c25ff4b
commit 8c64ef6
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Showing 2 changed files with 62 additions and 5 deletions.
diff --git a/js/bloch-sphere/model/BlochSphereModel.ts b/js/bloch-sphere/model/BlochSphereModel.ts
@@ -11,6 +11,7 @@ import BooleanProperty from '../../../../axon/js/BooleanProperty.js';
 import Multilink from '../../../../axon/js/Multilink.js';
 import NumberProperty from '../../../../axon/js/NumberProperty.js';
 import Property from '../../../../axon/js/Property.js';
+import dotRandom from '../../../../dot/js/dotRandom.js';
 import Range from '../../../../dot/js/Range.js';
 import TModel from '../../../../joist/js/TModel.js';
 import { EmptySelfOptions } from '../../../../phet-core/js/optionize.js';
@@ -55,9 +56,14 @@ export default class BlochSphereModel implements TModel {
   // If is single or multiple measurement mode
   public isSingleMeasurementModeProperty: BooleanProperty;
 
-  // If the model is ready to observe or needs the state to be prepared.
+  // A flag that indicates whether the model is ready to observe or needs the state to be prepared.  This should not be
+  // modified directly by client code, but rather by the model's observe() and reprepare() methods.
   public readonly readyToObserveProperty: BooleanProperty;
 
+  // Properties for the spin measurements made.
+  public readonly upMeasurementCountProperty: NumberProperty;
+  public readonly downMeasurementCountProperty: NumberProperty;
+
   public constructor( providedOptions: QuantumMeasurementModelOptions ) {
 
     this.selectedSceneProperty = new Property( BlochSphereScene.MEASUREMENT, {
@@ -116,6 +122,16 @@ export default class BlochSphereModel implements TModel {
       phetioReadOnly: true
     } );
 
+    this.upMeasurementCountProperty = new NumberProperty( 0, {
+      tandem: providedOptions.tandem.createTandem( 'upMeasurementCountProperty' ),
+      phetioReadOnly: true
+    } );
+
+    this.downMeasurementCountProperty = new NumberProperty( 0, {
+      tandem: providedOptions.tandem.createTandem( 'downMeasurementCountProperty' ),
+      phetioReadOnly: true
+    } );
+
     let selectingStateDirection = false;
     this.selectedStateDirectionProperty.link( stateDirection => {
       if ( stateDirection !== StateDirection.CUSTOM ) {
@@ -147,6 +163,7 @@ export default class BlochSphereModel implements TModel {
       }
     );
 
+    // Set the precession rate of the Bloch sphere based on the magnetic field strength and the selected scene.
     Multilink.multilink(
       [ this.magneticFieldStrengthProperty, this.selectedSceneProperty ],
       ( magneticFieldStrength, selectedScene ) => {
@@ -165,10 +182,46 @@ export default class BlochSphereModel implements TModel {
     } );
   }
 
+  /**
+   * Make whatever observation ths mode is currently set up to make.
+   */
+  public observe(): void {
+    if ( this.readyToObserveProperty.value ) {
+
+      // TODO: This code is a placeholder for the actual measurement logic.  See https://github.com/phetsims/quantum-measurement/issues/54.
+      const isUp = dotRandom.nextDouble() < 0.5;
+      if ( isUp ) {
+        this.upMeasurementCountProperty.value++;
+      }
+      else {
+        this.downMeasurementCountProperty.value++;
+      }
+
+      // Update the measurement state.
+      this.readyToObserveProperty.value = false;
+    }
+  }
+
+  /**
+   * Reprepare the model for a new observation.
+   */
+  public reprepare(): void {
+    this.readyToObserveProperty.value = true;
+  }
+
+  /**
+   * Resets the measurement counts.
+   */
+  private resetCounts(): void {
+    this.upMeasurementCountProperty.reset();
+    this.downMeasurementCountProperty.reset();
+  }
+
   /**
    * Resets the model.
    */
   public reset(): void {
+    this.resetCounts();
     this.preparationBlochSphere.reset();
     this.selectedSceneProperty.reset();
     this.readyToObserveProperty.reset();

diff --git a/js/bloch-sphere/view/BlochSphereMeasurementArea.ts b/js/bloch-sphere/view/BlochSphereMeasurementArea.ts
@@ -10,7 +10,6 @@
 
 import DerivedProperty from '../../../../axon/js/DerivedProperty.js';
 import DerivedStringProperty from '../../../../axon/js/DerivedStringProperty.js';
-import NumberProperty from '../../../../axon/js/NumberProperty.js';
 import { EmptySelfOptions } from '../../../../phet-core/js/optionize.js';
 import WithRequired from '../../../../phet-core/js/types/WithRequired.js';
 import PhetFont from '../../../../scenery-phet/js/PhetFont.js';
@@ -73,8 +72,8 @@ export default class BlochSphereMeasurementArea extends Node {
     );
 
     const measurementResultHistogram = new QuantumMeasurementHistogram(
-      new NumberProperty( 1 ),
-      new NumberProperty( 1 ),
+      model.upMeasurementCountProperty,
+      model.downMeasurementCountProperty,
       [
         new RichText( spinUpLabelStringProperty ),
         new RichText( spinDownLabelStringProperty ) ],
@@ -147,7 +146,12 @@ export default class BlochSphereMeasurementArea extends Node {
       prepareObserveButtonTextProperty,
       {
         listener: () => {
-          model.readyToObserveProperty.value = !model.readyToObserveProperty.value;
+          if ( model.readyToObserveProperty.value ) {
+            model.observe();
+          }
+          else {
+            model.reprepare();
+          }
         },
         baseColor: QuantumMeasurementColors.experimentButtonColorProperty,
         font: new PhetFont( 18 ),