How to stop my rigidbody immediatly when pressing Q,Im trying to stop my rigid body immediatly when pressing Q

This is the code

 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.Diagnostics;
 using System.Linq.Expressions;
 using UnityEngine;
 
 public class Dash : MonoBehaviour {
 
     float cooldown ; //Cooldown added to prevent double jump 
     // Use this for initialization
     void Start () {
         cooldown = 0;
     }
     
     // Update is called once per frame
     void Update () {
         if (Input.GetKeyDown(KeyCode.Space) && cooldown < 0) // Jump if the cooldown ended
             {
             GetComponent<Rigidbody>().AddForce(new Vector3(0, 300, 0));
             cooldown = 2;
             }
         else
         {
             cooldown = cooldown - 1 * Time.deltaTime;
 
         }
 
         if (Input.GetKeyDown(KeyCode.Q)) // Where I would like your help
         {
 
         }
     }
 }