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
		{

		}
	}
}

Sorry for the title, copy paste error

Try GetComponent<Rigidbody>().velocity = Vector3.zero;